. _:b509567438 . _:b19557110 . . _:b19557129 . _:b19557158 . _:b19557108 _:b19557109 . _:b19557111 . _:b19557108 _:b19557110 . _:b19557148 "This is consistent with S-type cells moving away from a neuronal phenotype; it has been found that after RA treatment S-type cells differentiate into Schwann cells [>>47<<] and also melanocytic cells [48]." . _:b19557108 _:b19557111 . _:b19557157 . _:b19557108 _:b19557116 . _:b19557108 _:b19557117 . _:b509567466 . _:b19557108 _:b19557118 . _:b19557108 _:b19557119 . _:b19557108 _:b19557112 . _:b19557108 _:b19557113 . _:b19557121 . _:b19557108 _:b19557114 . _:b19557161 "An increased expression of Bcl-2 has been associated with an inhibition of SOCE [52,>>53<<] and may therefore also play a role in SOCE down-regulation in N-type cells." . _:b19557108 _:b19557115 . _:b19557121 . . _:b19557117 . _:b19557124 . _:b19557122 . . _:b509567460 . . _:b19557165 "Multiple studies have implicated the involvement of SOCE proteins in proliferation [55\u2013>>58<<] and in differentiation [51,59,60]." . . _:b19557137 . _:b509567437 "2"^^ . _:b19557157 "TRPC1 has been found to function as a SOC when associated with STIM1 [28,30,>>31<<] and may therefore function as a SOC in proliferating N-type cells, however this was not determined." . _:b19557138 "RA treatment inhibits proliferation of cells [>>10<<] and a reduction in the rate of proliferation by ~\u00A075% in N-type cells and by ~\u00A050% in S-type cells was observed." . _:b509567436 "2"^^ . . . _:b509567439 "2"^^ . . _:b509567438 "2"^^ . _:b19557130 "Cell populations were induced to differentiate by the addition of 9cRA and characterised morphologically and biochemically using the neuronal marker proteins \u03B2-tubulin III and Bcl-2 [36\u201339] and the non-neuronal marker protein vimentin [>>3<<]. The remodelling of SOCE observed following 9cRA-induced differentiation [19] was further characterised in this study by determining the extent that N- and S-type cells contribute to the down-regulation." . _:b19557127 "Accumulating evidence suggests that SOCs are heteromeric complexes that can include both Orai1 and TRPC1 [29,31,33,>>34<<]." . _:b509567463 . . _:b509567433 "3"^^ . . _:b19557151 . . _:b509567444 . . _:b509567432 "4"^^ . . _:b509567435 "3"^^ . _:b19557119 . _:b509567434 "3"^^ . _:b19557146 . _:b19557139 "In order to determine cell lineage, fixed cells were stained with antibodies directed against \u03B2-tubulin III, a component of microtubules in neuronal cells [38,>>39<<] and vimentin, an intermediate filament protein in non-neuronal cells [3]." . _:b509567445 "2"^^ . _:b19557110 "At least three cellular phenotypes have been identified in neuroblastoma cell lines; neuroblastic N-type cells, substrate-adherent S-type cells and intermediate I-type cells [2\u2013>>5<<]. N-type cells are immature nerve cells, precursors to the sympathoadrenal cell lineage of the neural crest [4\u20136]. S-type cells are multipotent precursors to Schwann cells, melanocytes and glial cells and form the non-neuronal lineage of" . _:b509567469 . _:b509567444 "2"^^ . _:b19557126 "The interaction between STIM1 and TRPC1 can also require Orai1 [29,31\u2013>>34<<]. Accumulating evidence suggests that SOCs are heteromeric complexes that can include both Orai1 and TRPC1 [29,31,33,34]." . _:b509567437 . _:b509567450 . _:b509567447 "2"^^ . . _:b509567436 . _:b19557142 "This result is comparable to that seen in the parental SH-SY5Y cell line (Fig.\u00A04A), and also that previously observed in this laboratory [>>19<<]." . _:b509567446 "2"^^ . _:b19557137 . . _:b509567432 . _:b19557132 . _:b19557116 . _:b509567439 . _:b19557161 . . _:b509567441 "2"^^ . . _:b509567438 . _:b509567440 "2"^^ . _:b19557125 . . . _:b509567433 . _:b509567443 "2"^^ . _:b19557143 . _:b509567461 . _:b19557136 . _:b19557139 . _:b509567432 . _:b509567442 "2"^^ . _:b19557141 . _:b19557113 "I-type cells are intermediate with respect to N- and S-type cells in terms of morphology and biochemical markers [3,>>4<<]. I-type cells may represent either a stem cell or an intermediate stage in the transdifferentiation between N- and S-type cells [3,7]. N-type cells are more malignant than S-type cells, which appear to be non-malignant [5,8,9]. Retinoic" . . . _:b509567435 . _:b509567453 "2"^^ . . _:b19557144 . _:b509567457 . _:b509567434 . _:b509567452 "2"^^ . . _:b509567437 . _:b509567445 . _:b509567455 "2"^^ . _:b509567444 . _:b509567454 "2"^^ . _:b509567443 . _:b509567447 . . _:b509567449 "2"^^ . . . . . _:b509567446 . _:b509567448 "2"^^ . _:b19557149 . . _:b509567441 . _:b19557125 . _:b509567451 "2"^^ . _:b19557140 "In order to determine cell lineage, fixed cells were stained with antibodies directed against \u03B2-tubulin III, a component of microtubules in neuronal cells [38,39] and vimentin, an intermediate filament protein in non-neuronal cells [>>3<<]. \u03B2-tubulin III was present throughout the cytoplasm and along neurite branches/extensions of both proliferating and differentiated N-type cells; expression did not appear to change after 9cRA-induced differentiation (Fig." . _:b19557162 . _:b19557118 "The second messenger Ca2\u00A0+ plays an essential role in the regulation of many cellular processes [13,14], including differentiation of neuronal cells [15,>>16<<]. Store-operated Ca2\u00A0+ entry (SOCE) is a ubiquitous Ca2\u00A0+ influx pathway through which Ca2\u00A0+ enters cells via store-operated Ca2\u00A0+ channels (SOCs) located in the plasma membrane (PM) in response to depletion of endoplasmic reticulum (ER)" . _:b509567440 . _:b509567450 "2"^^ . _:b509567443 . _:b509567461 "2"^^ . . _:b19557144 "discussion" . _:b19557132 "materials and methods" . _:b19557119 "+ entry (SOCE) is a ubiquitous Ca2\u00A0+ influx pathway through which Ca2\u00A0+ enters cells via store-operated Ca2\u00A0+ channels (SOCs) located in the plasma membrane (PM) in response to depletion of endoplasmic reticulum (ER) Ca2\u00A0+ stores [17,>>18<<]. Previous work from this laboratory has shown that SOCE becomes down-regulated in SH-SY5Y neuroblastoma cells following 9-cis retinoic acid (9cRA)-induced differentiation [19]." . _:b509567442 . _:b509567460 "2"^^ . _:b19557127 . _:b19557116 . _:b509567453 . "10.1016%2Fj.bbamcr.2012.11.025" . _:b19557126 . . _:b509567463 "2"^^ . _:b19557140 . _:b509567452 . _:b509567462 "2"^^ . _:b19557125 . _:b509567455 . _:b509567457 "2"^^ . _:b19557134 "[Ca2\u00A0+]i was calculated using PerkinElmerWinLab\u00AE software which uses the formula of Grynkiewicz [>>40<<] which assumes a dissociation constant (Kd) of 224\u00A0nm and an instrument constant (IC) of 3." . _:b509567467 . _:b509567454 . _:b19557114 "I-type cells may represent either a stem cell or an intermediate stage in the transdifferentiation between N- and S-type cells [3,>>7<<]. N-type cells are more malignant than S-type cells, which appear to be non-malignant [5,8,9]. Retinoic acid (RA) is used in the treatment protocol for high-risk neuroblastoma patients as it inhibits proliferation and induces" . . _:b509567456 "2"^^ . _:b19557147 . . _:b19557124 . _:b509567449 . _:b19557111 "N-type cells are immature nerve cells, precursors to the sympathoadrenal cell lineage of the neural crest [4\u2013>>6<<]. S-type cells are multipotent precursors to Schwann cells, melanocytes and glial cells and form the non-neuronal lineage of the neural crest [3,4]. I-type cells are intermediate with respect to N- and S-type cells in terms of morphology" . _:b509567459 "2"^^ . . . . _:b19557125 . _:b509567448 . _:b19557123 . _:b509567458 "2"^^ . _:b509567460 . _:b19557166 . _:b509567461 . _:b19557156 . _:b19557126 . _:b509567451 . _:b509567462 . _:b509567469 "2"^^ . _:b509567463 . _:b509567456 . _:b19557150 . _:b19557126 . _:b509567446 . _:b19557127 . _:b509567457 . _:b509567450 . _:b509567458 . _:b509567468 "2"^^ . . _:b509567459 . _:b509567468 . _:b19557127 . _:b509567469 . _:b19557166 . _:b19557120 . _:b509567461 . _:b509567470 . _:b509567464 . _:b509567465 . _:b19557121 . _:b509567460 . _:b509567466 . _:b509567470 "2"^^ . _:b509567467 . _:b509567444 . _:b509567445 . _:b19557122 . _:b19557108 _:b19557124 . _:b509567463 . _:b19557108 _:b19557125 . _:b509567446 . _:b509567465 "2"^^ . _:b19557108 _:b19557126 . _:b509567447 . _:b509567470 . _:b19557141 . _:b19557108 _:b19557127 . _:b509567440 . _:b509567441 . _:b19557123 . _:b19557108 _:b19557120 . _:b509567462 . _:b19557164 "That remodelling of Ca2\u00A0+ signalling is a feature of the N-type cells could have important implications for neuroblastoma as tumours with a predominantly N-phenotype are more aggressive than tumours with a predominantly S-phenotype [>>2<<]. The down-regulation of SOCE in N-type cells may be required to either drive or maintain the switch from proliferation to differentiation, and the roles of STIM1, Orai1 and TRPC1 in this switch remain to be determined." . _:b19557108 _:b19557121 . _:b509567442 . _:b509567464 "2"^^ . _:b19557108 _:b19557122 . _:b509567443 . _:b19557109 "Neuroblastoma tumours and their derived cell lines are heterogeneous, composed of multipotent precursor cells that give rise to distinct neural crest cell lineages [>>2<<]. At least three cellular phenotypes have been identified in neuroblastoma cell lines; neuroblastic N-type cells, substrate-adherent S-type cells and intermediate I-type cells [2\u20135]. N-type cells are immature nerve cells, precursors to the" . _:b19557160 . _:b19557108 _:b19557123 . _:b509567452 . _:b509567453 . _:b19557156 "This is consistent with STIM1 as the ER Ca2\u00A0+ sensor [20,22] in both N- and S-type cells and with Orai1 forming, at least in part, the SOC [21,>>22<<] in both N- and S-type cells." . _:b19557132 . _:b19557141 . . _:b509567454 . _:b509567457 . _:b509567467 "2"^^ . _:b509567455 . _:b509567448 . _:b509567449 . _:b19557133 . _:b19557108 _:b19557128 . _:b509567456 . _:b19557108 _:b19557129 . _:b509567450 . _:b509567466 "2"^^ . _:b19557108 _:b19557130 . _:b509567451 . . _:b19557108 _:b19557131 . _:b19557134 . _:b509567459 . _:b19557135 . _:b19557165 . _:b509567458 . . . _:b509567436 . _:b509567437 . _:b19557128 . _:b509567469 . _:b509567438 . _:b509567439 . . _:b509567454 . _:b509567432 . . _:b19557129 . _:b509567433 . _:b509567468 . _:b509567434 . _:b509567435 . _:b19557122 . . _:b19557130 . _:b19557163 . _:b509567436 . _:b19557130 . . _:b19557121 . _:b19557143 . _:b19557131 . _:b509567470 . . _:b19557140 . _:b509567449 . _:b509567465 . . _:b19557141 . _:b19557115 "N-type cells are more malignant than S-type cells, which appear to be non-malignant [5,8,>>9<<]. Retinoic acid (RA) is used in the treatment protocol for high-risk neuroblastoma patients as it inhibits proliferation and induces differentiation of cells [10\u201312]." . _:b509567464 . _:b19557142 . _:b19557111 . _:b509567467 . _:b509567468 . _:b19557108 "introduction" . _:b19557143 . _:b509567466 . . . _:b19557136 . _:b19557153 . _:b19557162 "It may be that, as multi-potent precursors to several cell types [3,>>4<<], S-type cells represent sub-populations with variable SOC compositions." . _:b19557137 . _:b19557115 . . _:b19557138 . . _:b19557139 . . _:b19557108 . _:b19557148 . . _:b19557149 . _:b19557143 . . _:b19557141 "The expression of Bcl-2 was also determined as Bcl-2 has been shown to increase in differentiated neuroblastoma cells [44\u2013>>46<<]. Bcl-2 was expressed in proliferating SH-SY5Y and N-type cells and after 9cRA-induced differentiation became up-regulated by ~\u00A050% (P\u00A0=\u00A00.020, n\u00A0=\u00A06) and ~\u00A035% (P\u00A0=\u00A00.027, n\u00A0=\u00A07) respectively (Fig." . . _:b19557150 . _:b19557117 "The second messenger Ca2\u00A0+ plays an essential role in the regulation of many cellular processes [13,>>14<<], including differentiation of neuronal cells [15,16]." . _:b509567465 . _:b19557151 . _:b19557123 . _:b19557123 "Orai1 forms a SOC in many cell types and is required to reconstitute the Ca2\u00A0+ release-activated Ca2\u00A0+ current (ICRAC) [21,>>26<<], the most well-defined SOCE pathway." . _:b19557152 . _:b19557131 "The remodelling of SOCE observed following 9cRA-induced differentiation [>>19<<] was further characterised in this study by determining the extent that N- and S-type cells contribute to the down-regulation." . _:b19557133 . _:b19557144 . . _:b19557121 . _:b19557145 . _:b19557155 "This is consistent with STIM1 as the ER Ca2\u00A0+ sensor [20,>>22<<] in both N- and S-type cells and with Orai1 forming, at least in part, the SOC [21,22] in both N- and S-type cells." . . _:b19557133 "N- and S-type cells were enriched from the parental SH-SY5Y neuroblastoma cell line on the basis of their differential substrate adherence [>>8<<]. N-type cell populations were obtained by knocking off the more weakly adherent cells into PBS by gentle agitation and transferring the cell suspension to a new flask; S-type cell populations were obtained by maintaining those still" . _:b19557146 . _:b19557147 . _:b509567434 . _:b19557156 . _:b19557157 . _:b19557124 . _:b19557158 . _:b19557159 . _:b19557164 . _:b19557166 "Multiple studies have implicated the involvement of SOCE proteins in proliferation [55\u201358] and in differentiation [51,59,>>60<<]. It is likely that these proteins play a role in the differentiation process itself and may therefore provide a potential therapeutic target in the treatment of neuroblastoma." . _:b19557152 "The anti-apoptotic protein Bcl-2, which is widely expressed in sympathetic neurons [>>37<<], was present in proliferating N-type cells and became up-regulated in differentiated N-type cells [44\u201346], consistent with the neuronal lineage of the N-type cells." . _:b19557152 . _:b19557153 . _:b19557151 . _:b19557154 . . . _:b19557155 . _:b509567452 . . _:b19557164 . _:b19557165 . . _:b19557166 . . _:b19557160 . _:b19557139 . _:b19557154 . _:b19557165 . _:b19557161 . . . _:b19557114 . _:b19557162 . _:b19557121 "The proteins STIM1, Orai1 and TRPC1 have been reported to play a key role in SOCE [20\u2013>>23<<]. STIM1 senses the level of Ca2\u00A0+ within the ER and re-locates to ER-PM junctions to signal store depletion and induce opening of SOCs [24,25]." . _:b19557162 . _:b19557163 . _:b509567464 . _:b19557137 "Cells were classed as differentiated if neurite extensions were \u2265\u00A050\u00A0\u03BCm in length [19,42,>>43<<]. S-type cells differentiated into a more epithelial-like phenotype becoming larger and flatter with increased substrate adherence (Fig.\u00A01E). RA treatment inhibits proliferation of cells [10] and a reduction in the rate of proliferation by" . _:b19557148 . _:b19557124 "TRPC1 is a controversial SOC candidate as literature both supports and opposes the involvement of TRPC1 in SOCE [18,>>27<<]. TRPC1 may only function as a SOC under certain conditions as studies have shown that TRPC1 can function as either a SOC or a receptor-operated channel (ROC) depending on its interaction with STIM1 [28\u201330]. The interaction between STIM1" . . _:b19557159 . . . _:b19557153 . _:b19557129 . . . _:b19557129 . _:b19557149 "This is consistent with S-type cells moving away from a neuronal phenotype; it has been found that after RA treatment S-type cells differentiate into Schwann cells [47] and also melanocytic cells [>>48<<]." . _:b19557146 . _:b19557158 "In HEK293T cells down-regulation of STIM1 allowed TRPC1 to function as a ROC, insensitive to store depletion [>>30<<]. If TRPC1 functions as a ROC in differentiated N-type cells this could explain our previous observation that in 9cRA-differentiated SH-SY5Y cells a non-SOCE pathway becomes up-regulated [19]. TRPC1 may be associated with differentiation" . _:b509567433 . _:b19557116 "Retinoic acid (RA) is used in the treatment protocol for high-risk neuroblastoma patients as it inhibits proliferation and induces differentiation of cells [10\u2013>>12<<]." . . _:b19557127 . _:b509567453 . _:b19557108 . _:b19557126 . _:b19557109 . _:b19557145 "Previous findings from this laboratory have shown that SOCE becomes down-regulated in 9cRA-differentiated SH-SY5Y neuroblastoma cells [>>19<<]. The aims of this study were to characterise SOCE in N- and S-type cell populations and to investigate the involvement of STIM1, Orai1 and TRPC1 in relation to SOCE activity." . _:b19557126 . . _:b19557165 . _:b19557110 . . _:b19557122 "STIM1 senses the level of Ca2\u00A0+ within the ER and re-locates to ER-PM junctions to signal store depletion and induce opening of SOCs [24,>>25<<]. Orai1 forms a SOC in many cell types and is required to reconstitute the Ca2\u00A0+ release-activated Ca2\u00A0+ current (ICRAC) [21,26], the most well-defined SOCE pathway. TRPC1 is a controversial SOC candidate as literature both supports and" . _:b509567445 . . _:b19557111 . _:b19557151 "Vimentin is, however, an essential transient requirement for the initiation of neurite outgrowth in NB2a neuroblastoma cells and also in hippocampal neurons where knockdown of vimentin significantly inhibited neurite outgrowth [49,>>50<<]." . _:b19557118 . _:b19557166 . . _:b19557137 . . . . . _:b19557129 "Cell populations were induced to differentiate by the addition of 9cRA and characterised morphologically and biochemically using the neuronal marker proteins \u03B2-tubulin III and Bcl-2 [36\u2013>>39<<] and the non-neuronal marker protein vimentin [3]." . . _:b19557116 . . _:b19557117 . _:b19557135 . _:b19557142 . "PMC0" . _:b19557118 . _:b19557120 "Previous work from this laboratory has shown that SOCE becomes down-regulated in SH-SY5Y neuroblastoma cells following 9-cis retinoic acid (9cRA)-induced differentiation [>>19<<]." . _:b19557134 . _:b19557119 . _:b19557128 . _:b19557154 "The results revealed that the down-regulation of SOCE previously observed in SH-SY5Y cells [>>19<<], and also in this study, is a feature of N-type cells and not S-type cells." . _:b19557112 . _:b19557145 . . . _:b19557113 . . _:b19557113 . _:b19557114 . . _:b19557129 . _:b19557112 . _:b19557157 . _:b19557115 . _:b509567456 . _:b19557110 . _:b19557117 . . _:b19557156 . . _:b509567462 . _:b19557109 . _:b19557163 "The two states detected in proliferating cells could be as a result of covalent modifications, as has been observed with STIM1 [>>54<<]. Clearly the functional consequence of any covalent modifications needs to be elucidated." . _:b509567440 . _:b19557120 . _:b19557111 . _:b19557165 . _:b19557114 . _:b509567455 . _:b19557110 . _:b19557110 . _:b19557144 _:b19557148 . _:b19557144 _:b19557149 . _:b19557147 "S-type cells may have only recently committed to a non-neuronal lineage through the process of transdifferentiation [3,>>7<<]. Interestingly, \u03B2-tubulin III expression became further down-regulated in differentiated S-type cells. This is consistent with S-type cells moving away from a neuronal phenotype; it has been found that after RA treatment S-type cells" . _:b19557144 _:b19557150 . _:b19557144 _:b19557151 . _:b19557112 . _:b19557144 _:b19557145 . _:b19557144 _:b19557146 . _:b19557144 _:b19557147 . _:b19557113 . _:b19557144 _:b19557156 . _:b19557155 . _:b19557144 _:b19557157 . _:b19557144 _:b19557158 . _:b19557155 . _:b19557144 _:b19557159 . _:b19557144 _:b19557152 . _:b19557153 . _:b19557144 _:b19557153 . _:b19557146 "\u03B2-tubulin III, a microtubule protein found in neuronal cells [38,>>39<<], was expressed in N-type cells, and expression did not change following 9cRA-induced differentiation." . _:b19557144 _:b19557154 . _:b19557144 _:b19557155 . . _:b19557144 _:b19557164 . _:b509567442 . _:b19557144 _:b19557165 . _:b19557144 _:b19557166 . _:b19557144 _:b19557160 . _:b19557144 _:b19557161 . . _:b19557144 _:b19557162 . _:b19557144 _:b19557163 . _:b19557115 . _:b19557136 _:b19557140 . _:b19557136 _:b19557141 . _:b19557159 "If TRPC1 functions as a ROC in differentiated N-type cells this could explain our previous observation that in 9cRA-differentiated SH-SY5Y cells a non-SOCE pathway becomes up-regulated [>>19<<]. TRPC1 may be associated with differentiation itself; TRPC1 was required for neurite outgrowth in differentiating PC12 cells but was independent of SOCE [51]. TRPC1 expression was not detectable in either proliferating or differentiated" . _:b19557136 _:b19557142 . _:b509567451 . _:b19557136 _:b19557143 . _:b19557136 _:b19557137 . . _:b19557136 _:b19557138 . _:b19557160 "TRPC1 may be associated with differentiation itself; TRPC1 was required for neurite outgrowth in differentiating PC12 cells but was independent of SOCE [>>51<<]. TRPC1 expression was not detectable in either proliferating or differentiated S-type cells, which would indicate that TRPC1 does not function as a SOC in S-type cells. An increased expression of Bcl-2 has been associated with an" . . . _:b19557136 _:b19557139 . _:b19557125 "TRPC1 may only function as a SOC under certain conditions as studies have shown that TRPC1 can function as either a SOC or a receptor-operated channel (ROC) depending on its interaction with STIM1 [28\u2013>>30<<]. The interaction between STIM1 and TRPC1 can also require Orai1 [29,31\u201334]. Accumulating evidence suggests that SOCs are heteromeric complexes that can include both Orai1 and TRPC1 [29,31,33,34]." . _:b19557150 "Vimentin, an intermediate filament protein found in non-neuronal cells [>>3<<], was expressed in S-type cells. Vimentin was not generally expressed in N-type cells but it was identified in some neurite extensions." . . . _:b19557131 . _:b19557147 . _:b19557135 "The following equations were used; Fmin\u00A0=\u00A01\u00A0/\u00A0IC (Fmax\u00A0\u2212\u00A0FMn)\u00A0+\u00A0FMn and [Ca2\u00A0+]i\u00A0=\u00A0Kd(F\u00A0\u2212\u00A0Fmin)\u00A0/\u00A0(Fmax\u00A0\u2212\u00A0F) [>>40<<]. Each trace was calibrated individually to account for variation in confluency and/or fura-2 loading. To quantify change in [Ca2\u00A0+]i the area from each response was determined in calibrated traces using PerkinElmerWinLab\u00AE software. The" . . _:b19557112 "S-type cells are multipotent precursors to Schwann cells, melanocytes and glial cells and form the non-neuronal lineage of the neural crest [3,>>4<<]. I-type cells are intermediate with respect to N- and S-type cells in terms of morphology and biochemical markers [3,4]. I-type cells may represent either a stem cell or an intermediate stage in the transdifferentiation between N- and" . _:b19557161 . . _:b19557143 . _:b19557153 "The anti-apoptotic protein Bcl-2, which is widely expressed in sympathetic neurons [37], was present in proliferating N-type cells and became up-regulated in differentiated N-type cells [44\u2013>>46<<], consistent with the neuronal lineage of the N-type cells. Bcl-2 expression was barely detectable in both proliferating and differentiated S-type cells." . _:b509567459 . _:b19557132 _:b19557133 . _:b19557128 "and S-type cells were enriched from the parental SH-SY5Y neuroblastoma cell line which, although mainly composed of N-type cells, S-type cells remain present due to the ability of cells to transdifferentiate between cell phenotypes [7,>>35<<]. Cell populations were induced to differentiate by the addition of 9cRA and characterised morphologically and biochemically using the neuronal marker proteins \u03B2-tubulin III and Bcl-2 [36\u201339] and the non-neuronal marker protein vimentin" . _:b509567448 . _:b19557132 _:b19557134 . _:b19557143 "The proteins STIM1, Orai1 and TRPC1 have previously been shown to play a key role in SOCE [20\u2013>>23<<]. To determine whether these proteins were involved in the SOCE activity measured in N- and S-type cells, their expression was measured by western blot analysis." . _:b19557132 _:b19557135 . . _:b509567441 . _:b19557136 "results" . _:b509567458 . . _:b19557116 . _:b19557157 . _:b19557138 . . _:b19557126 . _:b19557119 . _:b19557127 . . . . _:b19557118 . _:b509567435 . _:b19557115 . . _:b509567439 . _:b509567447 .