_:b416360901 "3"^^ . _:b416360900 "3"^^ . _:b416360903 "3"^^ . _:b416360846 . _:b416360902 "3"^^ . _:b416360850 . . _:b416360897 "3"^^ . _:b416361003 . _:b416361079 . . _:b416360896 "3"^^ . _:b416361013 . _:b416361103 . _:b416361115 . _:b416360899 "3"^^ . _:b416360898 "3"^^ . . . _:b416360909 "3"^^ . _:b416360908 "3"^^ . _:b416360906 . . _:b416360787 . . _:b416360911 "3"^^ . . . _:b416360910 "3"^^ . _:b416361099 . _:b416360889 . _:b416360970 . _:b416360905 "3"^^ . _:b416361044 . _:b416361089 . _:b416360867 . _:b416361064 . _:b416360904 "3"^^ . . _:b416360907 "3"^^ . _:b416360906 "3"^^ . . _:b416360917 "2"^^ . _:b416360821 . _:b416360916 "2"^^ . _:b416360994 . _:b416360919 "2"^^ . . _:b416360918 "2"^^ . . _:b416360913 "2"^^ . _:b6235680 "As proposed recently>>46<<, nutrient-rich uncompacted soft ocean sediments ~2 billion years ago provided a selective evolutionary pressure favoring those very earliest eukaryotes that were better able to perform mechanical functions of invasion, crawling and" . _:b416360959 . _:b6235675 . . _:b416360912 "3"^^ . _:b416360915 "2"^^ . . . _:b416360965 . _:b416360914 "2"^^ . . _:b416360964 . _:b416360975 . _:b416360925 "2"^^ . _:b416361050 . _:b416360967 . _:b416360924 "2"^^ . _:b6235635 "Cell stiffness measurement technique is described before18,25,>>26<<,44,48,50. The cell complex softness is defined as the ratio of strain to the applied stress (i.e., the applied specific torque) and thus is the inverse of the cell complex stiffness." . _:b416360919 . _:b416360966 . . _:b416360927 "2"^^ . _:b6235681 . _:b416360961 . _:b6235643 "T3 stably was selected by puromycin (2 \u03BCg/ml; Invitrogen). DsRed.T3 has no toxicity in mouse ES cells>>52<<." . _:b416361037 . _:b416360926 "2"^^ . _:b416360960 . . _:b416360921 "2"^^ . _:b416360963 . _:b416360860 . _:b416360920 "2"^^ . _:b416360962 . _:b416361016 . . _:b416360923 "2"^^ . _:b416360973 . _:b416361108 . _:b416360922 "2"^^ . _:b416361018 . _:b6235658 "Our finding that stress-induced spreading in these mES cells depends on Cdc42 but not on Rac is interesting since it is well known that integrin-mediated cell spreading depends on Rac in differentiated cells32,>>33<<." . _:b416360972 . _:b416360933 "2"^^ . _:b416360975 . . _:b416360932 "2"^^ . _:b416360974 . _:b416360935 "2"^^ . _:b6235648 "its associated proteins, providing a biological consequence and a functional significance to the recent findings on stress-induced conformational changes and/or unfolding of signaling molecules28 and focal adhesion structural proteins>>15<<." . _:b416360969 . _:b416360794 . _:b416360934 "2"^^ . _:b416360968 . _:b416360806 . _:b416360929 "2"^^ . _:b416360971 . _:b416361122 . _:b416360928 "2"^^ . _:b416360970 . _:b416360931 "2"^^ . _:b416361135 . . _:b6235630 "Magnetic twisting cytometry (MTC) is a well established method for applying controlled and precise local mechanical stresses of physiologic magnitudes to a living cell18,26,>>44<<,48, 50." . _:b416360981 . _:b416360930 "2"^^ . _:b416360783 . _:b416360980 . _:b416360941 "2"^^ . _:b416360983 . . _:b416360940 "2"^^ . _:b416360795 . _:b416360982 . _:b416360943 "2"^^ . _:b416360875 . _:b416360977 . _:b6235647 "is the deformation of the cytoskeleton and its associated proteins, providing a biological consequence and a functional significance to the recent findings on stress-induced conformational changes and/or unfolding of signaling molecules>>28<< and focal adhesion structural proteins15." . _:b416360942 "2"^^ . _:b416360976 . _:b416360937 "2"^^ . _:b416360979 . _:b416360936 "2"^^ . . _:b416360978 . . _:b416361070 . _:b416361063 . _:b416360939 "2"^^ . . _:b416360989 . _:b416360938 "2"^^ . _:b416361065 . _:b416360988 . _:b416360949 "2"^^ . . _:b416360991 . _:b416360948 "2"^^ . . _:b416360990 . _:b416360951 "2"^^ . _:b416360985 . _:b6235671 "It is likely that time-varying, strain-dependent conformational changes and/or unfolding of these protein molecules at focal adhesions40 and at other distant sites>>41<< (e.g., inside the nucleus) are the primary molecular mechanisms of mechanochemical transduction and strain-activated feedback loops42." . _:b416361086 . _:b416360808 . _:b416360950 "2"^^ . _:b416360841 . _:b416360984 . _:b416360945 "2"^^ . _:b416360987 . _:b416360944 "2"^^ . _:b416360986 . _:b416360947 "2"^^ . . _:b416360997 . _:b416360946 "2"^^ . _:b416360996 . _:b416360957 "2"^^ . _:b416360920 . _:b416360999 . _:b416360980 . . _:b416360981 . _:b416360956 "2"^^ . . _:b416360982 . _:b416360983 . _:b416360998 . _:b416360976 . _:b416360977 . _:b416360959 "2"^^ . _:b416360978 . _:b416360979 . _:b416360993 . _:b416360988 . _:b416360989 . _:b416360958 "2"^^ . . _:b416360990 . _:b416360991 . _:b416360992 . _:b416360984 . _:b416360985 . _:b416360953 "2"^^ . _:b416360986 . _:b416361001 . _:b416360987 . _:b416360995 . _:b416360964 . _:b416360965 . _:b416360952 "2"^^ . _:b416360966 . _:b416360967 . _:b416360994 . _:b416360960 . _:b416360961 . _:b416360955 "2"^^ . . _:b416360962 . _:b6235667 "Currently it remains elusive what are the intracellular molecular strain sensor(s) in a live cell, although the extracellular domains of integrins have been shown to undergo force-dependent conformational change to enhance adhesion>>19<<, possibly via the catch bond mechanism39. However, accumulating evidence points to the deformation of focal adhesion proteins and possibly other structural proteins as the molecular mechanism of strain sensing." . _:b416360963 . _:b416361005 . _:b416360872 . _:b416360972 . _:b416360973 . _:b416360954 "2"^^ . _:b416360974 . _:b416360975 . _:b416361004 . _:b416360968 . _:b416360969 . _:b416360970 . _:b416360971 . _:b416361007 . _:b416361012 . _:b416361013 . . _:b416361014 . _:b416361015 . _:b416361006 . _:b416360812 . _:b416361008 . _:b416361009 . _:b416361010 . _:b416361011 . _:b416361001 . _:b416361020 . _:b416361021 . _:b416361022 . _:b416361023 . _:b416361000 . _:b416361016 . _:b416361017 . _:b416361018 . _:b416361019 . _:b416361003 . _:b416360996 . . . _:b416360997 . _:b416360998 . _:b416360999 . _:b416361002 . . _:b416360992 . _:b416360993 . _:b416360994 . _:b6235666 _:b6235680 . _:b416360995 . _:b416361013 . _:b6235666 _:b6235681 . _:b416361004 . _:b416361005 . _:b416361006 . . _:b416361007 . _:b416361052 . _:b416361012 . _:b416361000 . _:b416361001 . _:b416361002 . _:b6235652 . _:b416361003 . _:b416361015 . _:b416361044 . _:b416361045 . _:b416361046 . _:b6235653 . _:b416361047 . _:b416361014 . _:b416361040 . _:b416360935 . _:b416361041 . _:b416361042 . _:b6235654 . _:b416361043 . _:b416361009 . _:b416360955 . _:b416361052 . _:b416361053 . _:b416360991 . _:b416361054 . _:b6235655 . _:b416361055 . _:b416361008 . _:b416361048 . _:b416361049 . _:b416361050 . _:b6235648 . _:b416361051 . _:b416361054 . _:b416361011 . _:b416361028 . _:b416361029 . _:b416361030 . _:b6235649 . _:b416361031 . _:b416361010 . _:b416361024 . . . _:b416361025 . _:b416361026 . _:b6235650 . _:b416361027 . _:b416361021 . _:b416361036 . _:b416361037 . _:b416361160 . _:b416361038 . _:b6235651 . _:b6235666 _:b6235676 . _:b416361039 . _:b416361020 . _:b6235666 _:b6235677 . _:b416361032 . _:b6235666 _:b6235678 . _:b416361033 . _:b6235666 _:b6235679 . _:b416361034 . _:b6235660 . _:b6235666 _:b6235672 . _:b416361035 . _:b416361023 . _:b6235666 _:b6235673 . _:b416361076 . . _:b6235666 _:b6235674 . _:b416361077 . _:b6235634 "Cell stiffness measurement technique is described before18,>>25<<,26,44,48,50. The cell complex softness is defined as the ratio of strain to the applied stress (i.e., the applied specific torque) and thus is the inverse of the cell complex stiffness." . . _:b6235666 _:b6235675 . _:b416360847 . _:b416361078 . _:b6235661 . _:b6235666 _:b6235668 . _:b416361079 . _:b416361022 . _:b6235666 _:b6235669 . _:b416361072 . _:b6235666 _:b6235670 . _:b416361073 . _:b6235666 _:b6235671 . _:b416361074 . _:b6235662 . _:b416361075 . _:b416361017 . _:b416361084 . _:b416361060 . _:b6235624 "methods" . _:b416361085 . _:b6235666 _:b6235667 . _:b416361086 . _:b6235663 . _:b416361087 . _:b416361016 . _:b416361080 . _:b416361081 . _:b416361082 . _:b6235656 . _:b6235659 _:b6235660 . _:b416361083 . _:b416361019 . _:b6235659 _:b6235661 . _:b416361060 . _:b6235659 _:b6235662 . _:b416361061 . _:b6235659 _:b6235663 . _:b416361062 . _:b6235657 . . _:b416361063 . _:b416361018 . . _:b416361056 . _:b416361057 . _:b416361131 . . _:b416361058 . _:b6235658 . _:b416361059 . _:b416361029 . _:b416361068 . _:b416361069 . _:b416361106 . _:b416361070 . _:b416361071 . _:b416361028 . _:b6235659 . _:b416361064 . _:b416361065 . . _:b416361066 . _:b6235668 . _:b416361067 . _:b416361031 . . _:b416361108 . _:b416360989 . _:b6235659 . _:b416361109 . _:b416361110 . _:b6235669 . . _:b6235659 _:b6235664 . _:b416361111 . _:b416361030 . . _:b6235659 _:b6235665 . _:b416361104 . . _:b416361105 . _:b416361106 . _:b6235670 . _:b416360805 . _:b416361107 . _:b416361025 . _:b6235666 . _:b416361116 . _:b416361117 . _:b416361118 . _:b416361118 . _:b6235671 . _:b416361030 . _:b416361119 . _:b416361116 . _:b416361024 . _:b416361112 . _:b416361113 . _:b416361114 . _:b6235664 . _:b416361133 . . _:b416361115 . _:b416361027 . _:b416361092 . _:b416361093 . _:b416361094 . _:b6235665 . _:b416361095 . _:b416361026 . _:b416361088 . . _:b416361089 . _:b416361090 . _:b416361091 . _:b416361037 . _:b6235666 . _:b416361100 . _:b416361101 . . _:b416361102 . _:b6235667 . _:b416361103 . _:b416361036 . _:b416361096 . . _:b416361097 . _:b416360972 . . _:b416361098 . _:b6235676 . _:b416361099 . _:b416361039 . _:b416361140 . _:b416361141 . _:b416360823 . _:b416361142 . _:b6235677 . _:b416360913 . _:b416361143 . _:b416361038 . . _:b416361136 . _:b416361137 . _:b416361138 . _:b6235678 . _:b416361159 . _:b416361139 . _:b416361033 . _:b416361148 . . . . _:b416361149 . . _:b416361150 . _:b6235679 . _:b416361151 . _:b416361032 . _:b416361144 . . _:b416361145 . _:b416361146 . _:b6235672 . _:b416361147 . _:b416361035 . _:b416360807 . _:b416361124 . _:b416360928 . _:b416361125 . _:b416361126 . _:b6235673 . . _:b416361127 . _:b416361034 . _:b416361120 . _:b416361121 . _:b416361122 . _:b6235674 . _:b416361123 . _:b416361045 . _:b416361132 . _:b416361133 . _:b416361113 . _:b416361134 . _:b6235675 . _:b416361135 . _:b416361044 . . _:b416361128 . _:b416361129 . _:b416361130 . _:b416361131 . _:b416361047 . _:b416361046 . _:b416360985 . _:b416361156 . . _:b416361041 . _:b416361162 . _:b416361040 . _:b416361031 . _:b6235680 . _:b416361043 . _:b416361058 . _:b416361156 . _:b416361157 . . _:b416361158 . _:b6235681 . _:b416360804 . _:b416361159 . _:b416361042 . _:b416361152 . _:b416361153 . . . _:b416361154 . _:b416361155 . _:b416361053 . _:b416361164 . _:b416361165 . . . _:b416361052 . _:b416361160 . . _:b416361161 . _:b416361162 . _:b416361163 . _:b416361055 . _:b416360855 . _:b416361054 . _:b416361049 . _:b416360926 . _:b416361048 . _:b416360883 . . _:b416361051 . . _:b416361071 . _:b416361000 . _:b416361050 . . . _:b416361061 . _:b416360900 . . _:b416361060 . _:b416361134 . . _:b416361063 . _:b416361062 . _:b416361057 . _:b416361056 . . . _:b416361059 . _:b416360845 . _:b416361058 . . _:b416361069 . _:b416361074 . . _:b416361068 . . . _:b416361071 . . _:b416361070 . _:b416360882 . _:b416360853 . . _:b416361065 . . . . _:b416361064 . _:b416361020 . _:b416361067 . _:b416361075 . _:b416361066 . . . _:b416361077 . _:b6235627 . _:b416361040 . _:b416361076 . . . _:b416361079 . _:b416361078 . _:b416360843 . . _:b416361073 . _:b416360777 . _:b416361072 . _:b416361075 . . _:b416360964 . . _:b416361074 . . _:b416361085 . _:b416360876 . _:b6235677 . . _:b416361084 . . _:b416361051 . _:b416361087 . . _:b416361086 . _:b6235678 . . _:b416361081 . . . _:b416360956 . _:b416361080 . . . _:b416361083 . _:b416361008 . _:b416360796 . . . _:b416361082 . _:b416360873 . _:b416361093 . _:b416361082 . _:b416361092 . _:b416360942 . _:b6235670 "It is likely that time-varying, strain-dependent conformational changes and/or unfolding of these protein molecules at focal adhesions>>40<< and at other distant sites41 (e.g., inside the nucleus) are the primary molecular mechanisms of mechanochemical transduction and strain-activated feedback loops42." . _:b416361095 . _:b416360779 . _:b416361094 . _:b416360770 . _:b6235650 . _:b416361089 . . _:b416360957 . _:b416361112 . _:b416361088 . . _:b416360963 . . _:b416361091 . _:b416360981 . _:b416361090 . . _:b416361150 . _:b416361101 . _:b416361029 . . _:b6235664 . _:b416361033 . _:b416361157 . _:b416361148 . . _:b416361100 . _:b416361103 . . _:b416361102 . _:b416360827 . _:b416361097 . . _:b416361138 . _:b416361096 . _:b416361099 . _:b6235641 "Micropatterned adhesive islands on soft polyacrylamide gels were produced following published methods>>27<<." . _:b416361098 . _:b416361109 . . _:b416361108 . . . _:b416361111 . _:b416361022 . _:b416361110 . . _:b416361105 . . _:b416361104 . _:b416360946 . . . _:b416361107 . . _:b416361106 . . . _:b416361094 . _:b416361117 . _:b416360960 . _:b416361116 . . . _:b416361119 . _:b416361118 . _:b416361113 . . _:b416360802 . _:b416360809 . _:b416361112 . _:b416360951 . _:b416360810 . . _:b416361115 . . _:b416360866 . . _:b416361114 . _:b416361125 . . _:b416361124 . . _:b416361127 . _:b416360997 . _:b416361126 . _:b416360927 . _:b6235673 "An important test of this hypothesis will be to extend the in vitro work of del Rio et al>>15<< to a live cell using physiologically relevant amplitudes of time-varying stresses." . _:b416361121 . . "PMC0" . _:b416361130 . _:b416361120 . _:b416361068 . . _:b416361123 . _:b416361143 . _:b416361122 . . _:b416361133 . . _:b416360881 . _:b416360976 . . _:b416361132 . _:b416360936 . _:b416361135 . _:b6235662 "Accumulating experimental evidence suggests that mechanical contractile forces play a role in development (reviewed in ref. >>36<<). However, inability to access animal embryonic cells during early development makes it difficult to determine how important mechanical forces are during early development of animals and how sensitive embryonic cells are to force." . . _:b416361134 . _:b416361129 . _:b416361128 . . _:b416361131 . . _:b416361130 . _:b416360803 . _:b416360837 . _:b416361141 . _:b416360992 . _:b416361097 . _:b416361119 . _:b416361140 . . _:b416361143 . . _:b416360862 . _:b416361142 . _:b416360884 . _:b416361137 . _:b416361136 . _:b6235639 "parameter here because molecular motors (e.g., myosin II) are force (the independent variable) generators and because strain-dependent opening of proteins are likely to be important in changing protein activities and cell functions>>15<<." . _:b416360798 . _:b416360788 . _:b416361139 . _:b416360902 . _:b416360917 . _:b416361138 . . . . . _:b416361149 . . _:b416361148 . . _:b416361151 . . _:b416361062 . _:b416360778 . _:b416361150 . _:b6235643 . _:b416360968 . . _:b416361145 . . . _:b416361144 . _:b6235646 "projected area that controls the spreading or protrusion sensitivity to stress, we plated ESD cells or ASM cells on micropatterned adhesive islands (25-\u03BCm diameter circles) on the 0.6 kPa substrate coated with high density of collagen->>127<<. Each ESD cell or each ASM cell on each island had a similar projected area as the mES cell on the 0.6 kPa substrate but was ~8 times stiffer." . _:b416361147 . _:b416361139 . _:b416361146 . . _:b416361012 . _:b416361157 . _:b6235638 "Cell stiffness measurement technique is described before18,25,26,44,48,>>50<<. The cell complex softness is defined as the ratio of strain to the applied stress (i.e., the applied specific torque) and thus is the inverse of the cell complex stiffness." . . _:b416360905 . . _:b416361156 . _:b416360848 . _:b416361159 . _:b416360833 . _:b416361158 . _:b6235668 "the intracellular molecular strain sensor(s) in a live cell, although the extracellular domains of integrins have been shown to undergo force-dependent conformational change to enhance adhesion19, possibly via the catch bond mechanism>>39<<. However, accumulating evidence points to the deformation of focal adhesion proteins and possibly other structural proteins as the molecular mechanism of strain sensing." . . _:b416361153 . . _:b416361152 . . . _:b416360980 . _:b416361155 . _:b416360851 . . _:b416361154 . _:b416361027 . . _:b416361165 . _:b416361096 . _:b416361164 . _:b416360880 . . . . _:b416360856 . _:b416360901 . _:b416361161 . _:b416360925 . _:b416360945 . . _:b416361160 . _:b416361163 . _:b416361011 . _:b416361162 . _:b416361107 . _:b6235655 "It is known that Cdc42 mediates cell filopodia extension and cell spreading>>32<<. To determine the role of Cdc42 in stress-induced mES cell spreading, we infected the mES cells with small hairpin RNA (shRNA) for Cdc42 using lentiviruses." . _:b6235627 "This technique is described before in details>>24<<. We utilized their approach (CellMAP) where input was a high contrast time lapse sequence (5 sec interval) of a single cell and the outputs were the normal cell edge velocity as a function of space (over entire arclength) and time, mean" . _:b416360842 . _:b416360937 . . _:b416361154 . _:b416360840 . _:b416360965 . . . _:b416360870 . _:b416360921 . . . . _:b416361055 . . _:b6235626 . _:b6235652 . _:b416360949 . . _:b416361042 . . _:b416361121 . _:b416360915 . . _:b416360950 . . _:b6235654 "Therefore these softer mES cells fail to spread in response to the applied stress, because cell spreading is a complex process that requires dynamic coordination of actin polymerization and myosin II>>29<<." . _:b416360953 . . . _:b416361084 . _:b6235651 . . . . . _:b416361161 . . _:b6235632 "Magnetic twisting cytometry (MTC) is a well established method for applying controlled and precise local mechanical stresses of physiologic magnitudes to a living cell18,26,44,48, >>50<<." . _:b6235647 . _:b416361102 . _:b416360835 . _:b6235658 . _:b416360788 . _:b416360789 . _:b416360790 . _:b416360791 . _:b416360784 . _:b416361147 . . _:b416360785 . _:b416360786 . _:b416360787 . _:b416360796 . _:b6235650 "Interestingly, pretreatment with NSC23766 (100 \u03BCM for 1hr), a specific inhibitor of Rac>>30<<,31, did not block stress-induced spreading, suggesting that Rac was not important in stress-induced spreading of mES cells (Fig." . _:b416360797 . _:b416360798 . . _:b416360799 . _:b416360792 . _:b416360838 . _:b6235660 . _:b416360793 . . _:b416360794 . _:b416360795 . . _:b416360772 . _:b416360773 . _:b416360774 . _:b416360775 . _:b416360965 "2"^^ . _:b416361048 . _:b416360770 . _:b416360771 . _:b416360964 "2"^^ . . _:b416360780 . . _:b416360781 . _:b416360782 . _:b416360783 . _:b416360967 "2"^^ . _:b416360776 . . _:b416360777 . _:b416360778 . _:b416360779 . _:b416361123 . _:b416360966 "2"^^ . _:b416360820 . _:b416360821 . _:b416360822 . _:b416360823 . _:b416360961 "2"^^ . . _:b416360816 . _:b416360817 . _:b416360818 . _:b416360819 . _:b416360960 "2"^^ . . _:b416360828 . _:b416360829 . _:b416360830 . _:b416360831 . _:b416360963 "2"^^ . _:b416360824 . _:b416360825 . _:b416360826 . _:b416360827 . _:b416360962 "2"^^ . . _:b416361104 . _:b416360804 . . _:b416360805 . _:b416360806 . _:b416360786 . _:b416360973 "2"^^ . _:b416360807 . . _:b416360800 . _:b416360863 . _:b416360801 . _:b416360802 . . _:b416360972 "2"^^ . _:b416360803 . . _:b416360812 . _:b416360813 . _:b6235655 . _:b416360814 . _:b416360815 . _:b416360975 "2"^^ . _:b416360808 . _:b416360809 . _:b6235656 "S8), Cdc42 knockdown correlated well with the abolishment of stress-induced spreading in these mES cells, consistent with published results in the role of Cdc42 in integrin-mediated spreading of differentiated cells>>32<<. Our finding that stress-induced spreading in these mES cells depends on Cdc42 but not on Rac is interesting since it is well known that integrin-mediated cell spreading depends on Rac in differentiated cells32,33." . . _:b416360810 . _:b416360811 . _:b416360974 "2"^^ . _:b416360852 . _:b416360853 . _:b416360854 . _:b416360855 . _:b416360969 "2"^^ . _:b416360848 . _:b416360849 . _:b416360850 . _:b416360851 . _:b416360968 "2"^^ . _:b416360860 . _:b416360916 . _:b416360996 . _:b416360971 . _:b416360861 . _:b416360862 . _:b416360863 . _:b416360971 "2"^^ . _:b416360856 . _:b416360865 . _:b416361151 . _:b416360857 . . _:b416360858 . _:b416360859 . _:b416360970 "2"^^ . _:b416360836 . _:b416360837 . _:b416360838 . _:b416360839 . _:b416360981 "2"^^ . _:b416360832 . _:b416360833 . _:b416360834 . _:b416360835 . _:b416360980 "2"^^ . _:b416360966 . _:b416360844 . _:b416360845 . _:b416360846 . _:b416360847 . _:b416360983 "2"^^ . _:b416360840 . _:b416360841 . _:b416360842 . _:b416360843 . _:b416361095 . _:b416360982 "2"^^ . . _:b416360884 . _:b416360885 . _:b6235672 "changes and/or unfolding of these protein molecules at focal adhesions40 and at other distant sites41 (e.g., inside the nucleus) are the primary molecular mechanisms of mechanochemical transduction and strain-activated feedback loops>>42<<. An important test of this hypothesis will be to extend the in vitro work of del Rio et al15 to a live cell using physiologically relevant amplitudes of time-varying stresses." . _:b416360886 . . _:b416360977 "2"^^ . _:b416360887 . . _:b416360880 . _:b416360881 . _:b416360882 . _:b416361164 . . _:b416360976 "2"^^ . . _:b416360883 . _:b416360785 . _:b416360892 . . _:b416360893 . _:b416360894 . _:b416360895 . _:b416360979 "2"^^ . _:b416360888 . _:b416360889 . _:b6235656 . . . _:b416360890 . _:b416360891 . _:b416360978 "2"^^ . _:b416360868 . _:b416360869 . _:b6235657 . _:b416360870 . _:b416360871 . _:b416360989 "2"^^ . _:b416360864 . _:b416360865 . _:b416360866 . _:b416360867 . _:b416360988 "2"^^ . _:b416360876 . _:b416360947 . _:b416360877 . _:b416360878 . . _:b416360991 "2"^^ . _:b416360879 . _:b416360872 . _:b416361091 . _:b416360873 . . _:b416360874 . _:b416360875 . _:b416360990 "2"^^ . . _:b416360916 . _:b416360917 . _:b416360918 . . _:b416360985 "2"^^ . _:b416360919 . _:b416360912 . _:b6235639 . . _:b416360913 . _:b416360914 . _:b416360915 . _:b416360984 "2"^^ . _:b416360924 . _:b416360925 . _:b416360926 . _:b416361142 . _:b416360927 . _:b416361009 . _:b416360987 "2"^^ . _:b416360920 . _:b416360921 . _:b6235637 . _:b416360922 . _:b416360923 . _:b416360986 "2"^^ . _:b416360773 . _:b416360900 . _:b416360901 . _:b416360902 . _:b416360903 . _:b416360997 "2"^^ . . _:b416360896 . _:b416360897 . _:b416360898 . _:b416360789 . _:b416360996 "2"^^ . _:b416360899 . . _:b416360908 . _:b416360909 . _:b416360910 . _:b416360911 . _:b416360999 "2"^^ . . _:b416360904 . _:b416360905 . _:b6235625 . _:b416360906 . _:b416360907 . _:b416360998 "2"^^ . _:b416360948 . _:b416360949 . _:b416360950 . _:b416360951 . _:b416360993 "2"^^ . _:b416360849 . _:b416360944 . _:b416360945 . _:b6235631 . . _:b416360946 . . _:b416360992 "2"^^ . _:b416360947 . _:b416360956 . _:b416360957 . _:b416360858 . _:b416360958 . _:b416360959 . _:b416360995 "2"^^ . _:b416360952 . _:b416360953 . _:b416360914 . _:b416360954 . _:b416360955 . _:b416360994 "2"^^ . . _:b416360932 . _:b416360933 . _:b416360934 . _:b416361077 . _:b416360935 . _:b416361005 "2"^^ . . _:b416360928 . _:b416360929 . . _:b416360930 . _:b416360931 . _:b416361004 "2"^^ . _:b416360940 . _:b416360941 . _:b416360942 . _:b416360943 . _:b416361007 "2"^^ . _:b416360936 . _:b416360937 . _:b416360938 . . _:b416361006 "2"^^ . _:b416360939 . _:b416361001 "2"^^ . _:b416361092 . . _:b416361000 "2"^^ . . _:b416361003 "2"^^ . _:b416361002 "2"^^ . . _:b6235674 "It might not be a coincidence that an unfertilized egg has a stiffness of ~10 Pa>>43<<, an ES cell has a stiffness of ~500 Pa (Supplementary Fig." . _:b416361013 "2"^^ . . _:b416361012 "2"^^ . _:b416361015 "2"^^ . . . . . _:b416361014 "2"^^ . _:b416360817 . . _:b416361056 . _:b416361009 "2"^^ . . _:b416361008 "2"^^ . _:b416361163 . _:b416361011 "2"^^ . _:b416361155 . _:b416361010 "2"^^ . . _:b416360934 . _:b416361021 "2"^^ . . _:b416361020 "2"^^ . . _:b416361023 "2"^^ . _:b416361022 "2"^^ . _:b416360800 . _:b416361006 . _:b416361017 "2"^^ . . _:b416361016 "2"^^ . _:b416361019 "2"^^ . . . _:b416361010 . _:b6235678 "Matching cell material property with that of its substrate is known to be critical in forming striation in skeletal muscle cells>>23<< and optimizing cadiomyocyte beating45, but stiffness matching may have broader implications." . _:b416361018 "2"^^ . . _:b6235624 _:b6235628 . _:b6235624 _:b6235629 . _:b416361067 . _:b416361029 "2"^^ . _:b6235624 _:b6235630 . _:b416360939 . _:b6235624 _:b6235631 . _:b6235624 _:b6235625 . _:b416361028 "2"^^ . . _:b6235624 _:b6235626 . _:b416360801 . _:b6235624 _:b6235627 . _:b6235624 _:b6235636 . _:b6235649 . _:b6235624 _:b6235637 . _:b416361031 "2"^^ . _:b6235624 _:b6235638 . _:b416360861 . _:b6235624 _:b6235639 . _:b6235624 _:b6235632 . _:b6235624 _:b6235633 . _:b416361030 "2"^^ . _:b6235624 _:b6235634 . _:b6235624 _:b6235635 . _:b416360930 . _:b416361025 "2"^^ . _:b6235661 . _:b6235624 _:b6235640 . _:b6235654 . . _:b6235624 _:b6235641 . _:b416361024 "2"^^ . _:b6235624 _:b6235642 . _:b6235624 _:b6235643 . . _:b416361027 "2"^^ . . _:b416361026 "2"^^ . _:b6235645 "S5), consistent with the established evidence that F-actin is a major determinant in cell stiffness>>26<<." . _:b6235638 . _:b416361144 . . _:b416361037 "2"^^ . . . _:b6235679 . _:b416360834 . _:b416361146 . _:b416360773 . _:b6235632 . _:b416361036 "2"^^ . _:b416360954 . _:b416360772 . _:b416361039 "2"^^ . . _:b416360819 . _:b416360775 . _:b416361038 "2"^^ . . _:b416360885 . _:b416360774 . _:b416361033 "2"^^ . . _:b416361032 "2"^^ . . . _:b416361035 "2"^^ . _:b416360771 . _:b416361034 "2"^^ . _:b6235644 _:b6235645 . _:b416361045 "2"^^ . _:b416360770 . _:b6235644 _:b6235646 . _:b416361129 . _:b6235644 _:b6235647 . _:b6235674 . _:b416360924 . _:b6235631 "Magnetic twisting cytometry (MTC) is a well established method for applying controlled and precise local mechanical stresses of physiologic magnitudes to a living cell18,26,44,>>48<<, 50." . _:b416360781 . _:b416361044 "2"^^ . . _:b416360780 . _:b416361047 "2"^^ . _:b416361036 . _:b416360783 . _:b416361046 "2"^^ . _:b416360893 . . _:b416360782 . _:b416361041 "2"^^ . . _:b416361093 . _:b416361028 . . _:b416361040 "2"^^ . _:b416360777 . _:b416360776 . _:b416361043 "2"^^ . . . _:b416360779 . _:b416361042 "2"^^ . . _:b416360820 . _:b416361053 "2"^^ . _:b416360778 . _:b416360888 . _:b416361114 . . _:b416360789 . _:b416361052 "2"^^ . . _:b416360788 . _:b416361055 "2"^^ . . . _:b416360791 . _:b416361054 "2"^^ . . _:b416360790 . _:b416361049 "2"^^ . _:b416361034 . . _:b416360785 . _:b416361048 "2"^^ . . _:b416361145 . _:b416360859 . . _:b416360784 . _:b416361051 "2"^^ . _:b416360787 . _:b416361050 "2"^^ . _:b416360786 . _:b416361061 "2"^^ . . . _:b416360797 . _:b416361060 "2"^^ . _:b416360943 . _:b416360830 . _:b416360775 . _:b416360796 . _:b416361063 "2"^^ . _:b416360962 . _:b416360799 . _:b416361062 "2"^^ . _:b416361120 . _:b416360978 . _:b416360811 . _:b6235628 "Magnetic twisting cytometry (MTC) is a well established method for applying controlled and precise local mechanical stresses of physiologic magnitudes to a living cell>>18<<,26,44,48, 50." . _:b6235625 "Cells were thawed and cultured as described previously>>48<<. In short, undifferentiated mouse embryonic stem (mES) cells (W4, 129/SvEv) were maintained in the standard culture condition in the presence of Leukaemia Inhibitory Factor (LIF; Chemicon)." . _:b416361057 "2"^^ . _:b416360798 . _:b416360793 . _:b416361056 "2"^^ . _:b416360887 . _:b416360792 . _:b416361059 "2"^^ . _:b416360795 . _:b416361058 "2"^^ . _:b416360794 . _:b416361069 "2"^^ . . _:b416360805 . _:b416361068 "2"^^ . _:b416360772 . _:b416361025 . . . _:b416360804 . _:b416361071 "2"^^ . _:b416360807 . _:b416361070 "2"^^ . . _:b416360806 . _:b416361065 "2"^^ . _:b416361014 . _:b416360801 . _:b416361064 "2"^^ . _:b416360987 . . _:b416360903 . _:b416360800 . _:b416361067 "2"^^ . . . _:b416360803 . _:b416361066 "2"^^ . . _:b416360802 . _:b416361077 "2"^^ . _:b416360982 . _:b6235634 . _:b416360813 . _:b416361076 "2"^^ . _:b416360988 . _:b416360784 . _:b416360824 . _:b416360814 . _:b416360812 . _:b416361079 "2"^^ . _:b6235677 "S2), a brain neural cell has a stiffness of ~100\u2013500 Pa12, a typical differentiated tissue cell (e.g., a smooth muscle cell) has a stiffness of 1\u20135 kPa44, a skeletal muscle cell has a stiffness of ~12 kPa>>23<<. The respective softness of various types of cells might manifest their different physiological functions and sensitivities to force in a multi-cellular organism. An evolutionary advantage for an early lineage cell to become stiffer as" . _:b416360815 . _:b416361078 "2"^^ . . . _:b416360814 . _:b416361073 "2"^^ . . . _:b416361072 "2"^^ . _:b416360832 . _:b416360809 . _:b6235649 "This result suggests that Src is critical in the initiation of stress-induced spreading, consistent with a published report on the role of Src in the spontaneous early spreading of adherent cells>>29<<. Interestingly, pretreatment with NSC23766 (100 \u03BCM for 1hr), a specific inhibitor of Rac30,31, did not block stress-induced spreading, suggesting that Rac was not important in stress-induced spreading of mES cells (Fig. 3a, Supplementary" . _:b416360808 . _:b416361075 "2"^^ . . . _:b416361059 . . _:b416360811 . _:b416361074 "2"^^ . _:b6235628 . _:b416360825 . _:b6235651 "Interestingly, pretreatment with NSC23766 (100 \u03BCM for 1hr), a specific inhibitor of Rac30,>>31<<, did not block stress-induced spreading, suggesting that Rac was not important in stress-induced spreading of mES cells (Fig." . _:b416361085 "2"^^ . _:b416360979 . _:b416360810 . _:b416360821 . _:b416361084 "2"^^ . . _:b416361090 . _:b416360820 . _:b416361087 "2"^^ . _:b416360948 . . _:b6235633 . . _:b416361086 "2"^^ . . _:b416360823 . . _:b416360822 . _:b416361081 "2"^^ . _:b416360817 . _:b416361080 "2"^^ . . _:b416361026 . _:b416360816 . _:b6235635 . _:b416361083 "2"^^ . . _:b416360819 . _:b416361082 "2"^^ . _:b416360897 . _:b416360910 . _:b416360818 . _:b416361093 "2"^^ . _:b416360895 . _:b416361092 "2"^^ . . _:b416360829 . _:b416360828 . _:b416361095 "2"^^ . . . _:b416361049 . _:b416360831 . _:b416361094 "2"^^ . . . _:b416360830 . _:b6235645 . _:b416361089 "2"^^ . . _:b416360825 . _:b416361088 "2"^^ . . _:b416360799 . _:b416360824 . _:b416361091 "2"^^ . . _:b6235669 "For example, in vitro forcing experiments show that unfolding single talin rods activates vinculin binding>>15<<. It is likely that time-varying, strain-dependent conformational changes and/or unfolding of these protein molecules at focal adhesions40 and at other distant sites41 (e.g., inside the nucleus) are the primary molecular mechanisms of" . _:b416360827 . _:b416361090 "2"^^ . . . _:b416360826 . _:b416361101 "2"^^ . _:b416360837 . _:b416361100 "2"^^ . _:b6235633 "Cell stiffness measurement technique is described before>>18<<,25,26,44,48,50. The cell complex softness is defined as the ratio of strain to the applied stress (i.e., the applied specific torque) and thus is the inverse of the cell complex stiffness." . . . _:b416361103 "2"^^ . _:b416360836 . . _:b416360818 . _:b6235680 . _:b416360839 . _:b416361102 "2"^^ . _:b416360904 . _:b416360838 . _:b416361097 "2"^^ . . _:b416360833 . _:b416361096 "2"^^ . _:b416360816 . _:b416360832 . _:b416361099 "2"^^ . _:b416360829 . _:b416360835 . _:b416361098 "2"^^ . . _:b416361109 "2"^^ . _:b416360834 . _:b416360845 . _:b416361108 "2"^^ . _:b416360844 . _:b416361111 "2"^^ . . _:b416360847 . _:b416361110 "2"^^ . _:b416360846 . _:b6235629 . _:b416361105 "2"^^ . _:b416360841 . _:b416361104 "2"^^ . . _:b416361078 . . _:b416360840 . _:b416361107 "2"^^ . . _:b416360940 . _:b416361127 . _:b416360839 . _:b416360843 . _:b416361106 "2"^^ . _:b416360958 . _:b6235666 "molecular mechanism of mechanotransduction" . _:b6235661 "Since loss of Oct3/4 expression in ES cells is one of the hallmarks for differentiation>>35<<, our results suggest that a local cyclic stress via a focal adhesion might be sufficient to drive a mES cell to differentiate." . _:b416360842 . _:b416361117 "2"^^ . _:b416360853 . _:b416361116 "2"^^ . _:b416361076 . _:b416360852 . _:b416361119 "2"^^ . _:b6235630 . _:b416361073 . _:b416360855 . _:b416361118 "2"^^ . . . _:b416360854 . _:b416361113 "2"^^ . _:b416361087 . _:b416360896 . _:b416360849 . _:b416361112 "2"^^ . _:b416360848 . _:b416361115 "2"^^ . . _:b416360851 . _:b416361114 "2"^^ . _:b416360831 . _:b6235659 "stress-induced mes cell differentiation" . _:b416360850 . _:b416361125 "2"^^ . _:b416360861 . _:b416361124 "2"^^ . _:b416360869 . _:b416360878 . _:b416360860 . _:b416361127 "2"^^ . . . _:b416361140 . _:b416360863 . _:b416361126 "2"^^ . . . _:b416360862 . _:b416361121 "2"^^ . . _:b6235636 . _:b416360857 . _:b416361120 "2"^^ . _:b6235642 . _:b6235676 . _:b416360856 . _:b416361123 "2"^^ . . _:b416361061 . _:b416360859 . _:b416361122 "2"^^ . . _:b416361053 . . . _:b416360858 . _:b416361133 "2"^^ . _:b416360869 . _:b416361132 "2"^^ . . . _:b6235636 "Cell stiffness measurement technique is described before18,25,26,>>44<<,48,50. The cell complex softness is defined as the ratio of strain to the applied stress (i.e., the applied specific torque) and thus is the inverse of the cell complex stiffness." . _:b416360868 . _:b416361135 "2"^^ . . _:b416361024 . _:b416360871 . _:b416361134 "2"^^ . _:b416360870 . _:b416361129 "2"^^ . . _:b416360865 . _:b416361128 "2"^^ . _:b416360894 . _:b416360983 . _:b416360864 . _:b416361131 "2"^^ . _:b416360867 . _:b416361130 "2"^^ . _:b416361101 . . _:b416361141 "2"^^ . _:b416360866 . _:b416360892 . _:b416360776 . _:b416360877 . _:b416361140 "2"^^ . _:b6235663 "In a recent review, Discher et al. discuss the combined effects of growth factors, matrices, and mechanical forces in controlling stem cells>>37<<. The importance of substrate stiffness in stem cell differentiation is highlighted. However, the underlying mechanism remains unclear. It has been reported that substrate elasticity modulates intracellular rheology: stiffer matrices" . _:b416360876 . _:b416361143 "2"^^ . _:b416361111 . _:b416360879 . _:b416361142 "2"^^ . _:b416361081 . _:b6235652 "S7), consistent with recent findings that rapid Src activation by stress only occurs via activated integrins>>28<< and that an applied stress via integrins induces additional activation of integrins and phosphorylation of focal adhesion kinase19." . _:b416360878 . _:b416361137 "2"^^ . _:b416360886 . _:b416360873 . _:b416361136 "2"^^ . _:b416360872 . _:b416361139 "2"^^ . . _:b416360875 . _:b416361138 "2"^^ . _:b416360874 . _:b416361149 "2"^^ . . _:b416360899 . _:b416360885 . _:b416361148 "2"^^ . _:b416360836 . _:b416360884 . _:b416361151 "2"^^ . _:b416361100 . _:b416360887 . _:b416361150 "2"^^ . "10.1038%2Fnmat2563" . . _:b416361145 "2"^^ . _:b416361019 . _:b416360886 . _:b416360998 . _:b416360881 . _:b416361144 "2"^^ . _:b416360961 . . . _:b416360880 . _:b416361147 "2"^^ . _:b6235665 . _:b416360929 . _:b416360883 . _:b416361146 "2"^^ . _:b416360882 . _:b416361157 "2"^^ . . _:b416360893 . _:b416361156 "2"^^ . _:b416361132 . _:b416360892 . _:b416361159 "2"^^ . _:b416360895 . _:b416361158 "2"^^ . _:b416361066 . _:b416360894 . _:b416361153 "2"^^ . _:b416360973 . _:b416361072 . _:b416360889 . _:b416361152 "2"^^ . . . _:b416361110 . . _:b416360888 . _:b416361155 "2"^^ . _:b416360891 . _:b416361154 "2"^^ . _:b416360898 . _:b416361137 . . _:b416361165 "2"^^ . _:b416360890 . . _:b416360852 . _:b6235629 "Magnetic twisting cytometry (MTC) is a well established method for applying controlled and precise local mechanical stresses of physiologic magnitudes to a living cell18,>>26<<,44,48, 50." . _:b416361164 "2"^^ . _:b416360901 . _:b416360891 . _:b416360900 . . _:b416360999 . _:b416360903 . . _:b416360797 . _:b416361161 "2"^^ . _:b416360902 . _:b416360897 . _:b416361160 "2"^^ . . _:b416360896 . _:b416361163 "2"^^ . _:b416360911 . _:b416361005 . _:b416360899 . _:b416361162 "2"^^ . _:b416361069 . _:b416360898 . . _:b416360909 . _:b6235663 . . _:b416361004 . . _:b416360908 . _:b416360874 . _:b416360911 . . . _:b416360910 . _:b416360905 . _:b416361083 . _:b416360904 . . _:b416360907 . . . _:b416360906 . _:b416361088 . _:b416360890 . _:b416360917 . _:b416360793 . _:b6235644 _:b6235652 . _:b6235644 _:b6235653 . _:b416360916 . _:b416360774 "10"^^ . _:b6235644 _:b6235654 . _:b416360770 "27"^^ . _:b6235644 _:b6235655 . _:b6235644 _:b6235648 . _:b6235640 "Cell traction measurements have been described in details elsewhere>>46<<. Generated traction maps were used for further quantification." . _:b416360775 "9"^^ . . _:b416360919 . _:b6235644 _:b6235649 . _:b416360773 "10"^^ . _:b6235644 _:b6235650 . _:b6235644 _:b6235651 . _:b6235671 . _:b416360864 . _:b416360918 . _:b416360772 "11"^^ . _:b6235644 _:b6235656 . _:b6235644 _:b6235657 . _:b416360913 . _:b6235644 _:b6235658 . . _:b416360771 "13"^^ . _:b416360912 . _:b6235626 "All our procedures were approved by the Institutional Review Board of University of Illinois at Urbana-Champaign. The ASM cells were cultured following published protocols>>28<<." . _:b416360915 . _:b6235660 "the long term effects of a local cyclic stress in mES cell functions, we examined the expression of stably transfected GFP driven by Oct3/4 promoter in undifferentiated cells cultured in the presence of leukaemia inhibitory factor (+LIF)>>34<<. After a continuous application of a 17.5-Pa local stress at 0.3 Hz for only 60 min, Oct3/4 expression in these mES cells was downregulated by ~35% within 24 hrs, and by ~50% within 72 hrs, whereas control cells a few micrometers away in" . _:b416360914 . . _:b416360925 . . _:b6235662 . _:b416360782 "8"^^ . . _:b416360924 . _:b416360783 "8"^^ . _:b416360927 . _:b416360854 . _:b416360780 "8"^^ . _:b416360926 . _:b416360781 "8"^^ . . _:b416360921 . _:b416361117 . _:b416360778 "8"^^ . _:b416360920 . _:b416361032 . _:b416360779 "8"^^ . _:b416360923 . . _:b416360776 "9"^^ . _:b416360922 . _:b416360777 "9"^^ . _:b416360933 . . _:b416360790 "6"^^ . _:b416360932 . _:b416360791 "6"^^ . _:b416360932 . _:b416360935 . _:b416360788 "6"^^ . _:b6235672 . _:b416360934 . _:b6235640 . _:b416360789 "6"^^ . . _:b416360909 . _:b416360929 . _:b416360786 "7"^^ . _:b416360928 . _:b416360787 "7"^^ . . _:b416360931 . . _:b416360784 "7"^^ . _:b416360984 . _:b416360930 . _:b416360785 "7"^^ . _:b416360941 . _:b416360931 . _:b416360797 "5"^^ . _:b416361035 . _:b416360940 . _:b416360796 "5"^^ . _:b416360943 . _:b416360826 . _:b416360942 . _:b416360799 "5"^^ . _:b416360798 "5"^^ . _:b416360937 . _:b416360794 "6"^^ . _:b416360923 . _:b416360936 . . . _:b416360939 . _:b416360792 "6"^^ . _:b416360844 . _:b6235665 "Our result that the cytoplasm of mES cells is intrinsically soft is also in accord with a previous finding that the nucleus of human ES cells is intrinsically soft>>38<<." . _:b416360795 "5"^^ . _:b416360938 . . _:b416360793 "6"^^ . . . . _:b416360912 . _:b416360949 . . _:b6235642 "A mouse ES cell line, namely OGR1, that expresses EGFP under the promoter of Oct3/4 (Oct3/4::EGFP)>>51<< was transfected with 0.5 \u03BCg of pCAGGSDsRedT3_T2A_Puro (T. S. Tanaka et al., unpublished results) with FuGene (Roche) according to the manufacturer." . _:b416360805 "5"^^ . _:b416360948 . . _:b416360804 "5"^^ . _:b416360951 . . _:b416360807 "4"^^ . _:b416360950 . _:b416361098 . . _:b416360806 "4"^^ . _:b416360945 . _:b6235653 "consistent with recent findings that rapid Src activation by stress only occurs via activated integrins28 and that an applied stress via integrins induces additional activation of integrins and phosphorylation of focal adhesion kinase>>19<<. Stress-induced spreading in mES cells were completely prevented by pre-treatment with Latrunculin A (0.1 \u03BCg/ml for 30 min), consistent with the role of actin polymerization in cell protrusion and spreading." . _:b416361165 . _:b416360801 "5"^^ . _:b416360944 . . _:b416360800 "5"^^ . _:b416360947 . . _:b416360803 "5"^^ . _:b416360946 . . . . _:b416360802 "5"^^ . _:b416360957 . _:b416360969 . _:b416360813 "4"^^ . _:b416361002 . _:b416360956 . . _:b416360812 "4"^^ . _:b416360959 . _:b416360774 . _:b416360815 "4"^^ . _:b416360958 . _:b416360814 "4"^^ . . _:b416360813 . _:b416360953 . . _:b416360809 "4"^^ . _:b6235653 . _:b416360952 . . _:b416360808 "4"^^ . _:b416360955 . . _:b416360811 "4"^^ . _:b416360954 . _:b416361153 . . _:b416360810 "4"^^ . _:b416360821 "4"^^ . _:b416361057 . _:b416360820 "4"^^ . _:b416360823 "4"^^ . _:b6235648 . _:b416360822 "4"^^ . . _:b416360817 "4"^^ . _:b6235664 "It has been reported that substrate elasticity modulates intracellular rheology: stiffer matrices result in stiffer cells>>7<<. In contrast, we show here that intracellular softness can determine cellular biological sensitivity to force at fixed substrate rigidity. Our current work reveals a biophysical mechanism of ES cells in dictating how ES cells respond" . _:b416360816 "4"^^ . . _:b416360819 "4"^^ . _:b416361085 . _:b416360818 "4"^^ . . _:b416360995 . . _:b416360829 "4"^^ . _:b416360993 . _:b416360828 "4"^^ . _:b416360831 "4"^^ . _:b6235679 "Matching cell material property with that of its substrate is known to be critical in forming striation in skeletal muscle cells23 and optimizing cadiomyocyte beating>>45<<, but stiffness matching may have broader implications." . _:b416360830 "4"^^ . _:b416361124 . _:b416360825 "4"^^ . _:b416360824 "4"^^ . _:b6235669 . . _:b416360827 "4"^^ . _:b416360815 . _:b416360826 "4"^^ . . _:b416360837 "4"^^ . . _:b416360828 . _:b416360836 "4"^^ . _:b416360941 . _:b416360792 . _:b416360986 . _:b416360839 "4"^^ . _:b6235667 . _:b416360838 "4"^^ . _:b416360857 . . _:b416360833 "4"^^ . _:b416360832 "4"^^ . _:b416361125 . _:b416360835 "4"^^ . _:b416360868 . . _:b416361021 . _:b416361045 . _:b416361041 . _:b416360834 "4"^^ . _:b416360845 "4"^^ . . _:b416361152 . _:b416360844 "4"^^ . _:b6235628 . _:b416361141 . _:b416360847 "3"^^ . _:b6235673 . _:b6235629 . . . . _:b6235630 . _:b416360846 "4"^^ . _:b416360841 "4"^^ . _:b6235631 . _:b416360840 "4"^^ . _:b6235624 . _:b6235670 . _:b416360843 "4"^^ . _:b6235625 . _:b416360842 "4"^^ . _:b6235626 . . . _:b416360853 "3"^^ . _:b6235627 . . _:b416361109 . _:b416360852 "3"^^ . _:b6235636 . _:b416360855 "3"^^ . _:b6235637 . _:b6235681 "to determine if these findings can be extended to human ES cells and induced pluripotent stem (iPS) cells, and to find out whether stress-induced signals inhibit known pluripotency-supporting pathways mediated by molecules such as mTOR>>47<<. It will also be interesting to determine what type of germ layer cells (endoderm, mesoderm, or ectoderm) can be derived from these soft ES cells by what mode of mechanical perturbations." . _:b416360854 "3"^^ . _:b6235638 . . . . _:b416360849 "3"^^ . _:b6235639 . . _:b416361136 . _:b416360848 "3"^^ . _:b6235675 "S2), a brain neural cell has a stiffness of ~100\u2013500 Pa>>12<<, a typical differentiated tissue cell (e.g., a smooth muscle cell) has a stiffness of 1\u20135 kPa44, a skeletal muscle cell has a stiffness of ~12 kPa23." . . _:b416360879 . _:b6235632 . _:b6235668 . _:b416361038 . _:b416360851 "3"^^ . _:b6235633 . _:b416360850 "3"^^ . _:b6235634 . . . _:b416360861 "3"^^ . _:b6235635 . . . _:b416360860 "3"^^ . _:b6235644 . . _:b416360863 "3"^^ . _:b6235644 "cell softness dictates response to stress" . _:b6235645 . _:b416361126 . _:b416360790 . _:b416360862 "3"^^ . _:b6235646 . _:b6235637 "Cell stiffness measurement technique is described before18,25,26,44,>>48<<,50. The cell complex softness is defined as the ratio of strain to the applied stress (i.e., the applied specific torque) and thus is the inverse of the cell complex stiffness." . _:b416360857 "3"^^ . _:b416360877 . _:b6235647 . . . . _:b6235676 "S2), a brain neural cell has a stiffness of ~100\u2013500 Pa12, a typical differentiated tissue cell (e.g., a smooth muscle cell) has a stiffness of 1\u20135 kPa>>44<<, a skeletal muscle cell has a stiffness of ~12 kPa23." . _:b416360856 "3"^^ . _:b6235640 . _:b416360974 . _:b416360859 "3"^^ . _:b6235641 . _:b6235657 "Our finding that stress-induced spreading in these mES cells depends on Cdc42 but not on Rac is interesting since it is well known that integrin-mediated cell spreading depends on Rac in differentiated cells>>32<<,33." . . _:b416360858 "3"^^ . . _:b6235642 . _:b416360908 . _:b416361015 . . _:b416360869 "3"^^ . _:b6235643 . _:b416360868 "3"^^ . _:b416360771 . . _:b416360871 "3"^^ . _:b416361046 . . _:b416360870 "3"^^ . . _:b416361149 . _:b6235646 . _:b416360865 "3"^^ . _:b416361007 . . _:b416360864 "3"^^ . _:b416360952 . . . _:b416360867 "3"^^ . . . _:b416361047 . _:b416360866 "3"^^ . _:b416361080 . _:b416361105 . _:b416361158 . _:b416360780 . . _:b416360877 "3"^^ . . . _:b416360782 . _:b416360876 "3"^^ . . . _:b416360781 . _:b416360879 "3"^^ . _:b416361043 . _:b6235641 . _:b416360878 "3"^^ . _:b416360907 . . . _:b416360873 "3"^^ . _:b416361017 . _:b416360933 . _:b416360872 "3"^^ . . . _:b416360875 "3"^^ . _:b416360871 . _:b416360977 . . _:b416360874 "3"^^ . _:b416360791 . . _:b6235624 . _:b416360885 "3"^^ . _:b416360938 . _:b416361023 . _:b416360884 "3"^^ . _:b416360990 . _:b416360887 "3"^^ . _:b6235644 . . _:b416360886 "3"^^ . _:b416360881 "3"^^ . . _:b416360922 . . _:b416360880 "3"^^ . . . _:b416360918 . _:b416360883 "3"^^ . _:b416360882 "3"^^ . _:b416360893 "3"^^ . _:b416361039 . _:b416360892 "3"^^ . _:b416361128 . . _:b416360895 "3"^^ . _:b416360944 . . _:b416360894 "3"^^ . _:b416360889 "3"^^ . _:b416360888 "3"^^ . . _:b416360967 . _:b416360822 . _:b416360891 "3"^^ . _:b416360890 "3"^^ . .