m-3M3FBS is a new compound that has been used as a phospholipase C (PLC) activator. The effect of m-3M3FBS on cytosolic free Ca2+ concentrations in human gastric cancer cells (SCM1) is unclear. This study explored whether m-3M3FBS changed basal [Ca2+]i levels in suspended SCM1 cells by using fura-2 as a Ca2+-sensitive fluorescent dye. m-3M3FBS at concentrations between 1-50 £gM increased [Ca2+]i in a concentration-dependent manner. The Ca2+ signal was reduced partly by removing extracellular Ca2+. This Ca2+ influx was inhibited by phospholiapase A2 inhibitor aristolochic acid , store-operated Ca2+ channel blockers nifedipine ¡B econazole and SK&F96365; and protein kinase C inhibitor GF109203X. Phorbol 12-myristate 13-acetate ([PMA] a protein kinase C activator) had no effect on m-3M3FBS-induced [Ca2+]i rise. In Ca2+-free medium , pretreatment with m-3M3FBS abolished thapsigargin (TG) or 2,5-di-tert-butylhydroquinone (BHQ) - induced [Ca2+]i rise. Conversely, pretreatment with the endoplasmic reticulum Ca2+ pump inhibitors TG or BHQ partly inhibited m-3M3FBS -induced Ca2+ release. The inhibition of PLC with U73122 did not alter mMIRC. Collectively, in SCM1 cells, mMIRC by causing PLCindependent Ca2+ release from the endoplasmic reticulum and Ca2+ influx via phospholipase A2-protein kinase C-sensitive store-operated Ca2+ channels.