Glucose-induced calcium entry is necessary for sAC activation. Cyclic AMP was measured in INS-1E cells after incubation for 15 min in 2.5 or 16 mM glucose in the presence of 0.5 mM IBMX, with either vehicle control (white bars) or (A) 100 μM EGTA-AM (gray bars), 300 μM diazoxide (black bars) or (B) 60 μM verapamil (black bars). Values represent means ± SEM (n ≥ 4). ANOVA statistical analyses were performed with the Newman-Keuls post-hoc test. ***, P < 0.001.