Effects of zinc supplementation on insulin gene expression, insulin content and insulin secretion. Insulin gene expression (A), intracellular insulin content (B), insulin secretion (C), and the insulin secretion/content ratio (D) were assessed after INS-1E cells were stimulated with 20 μM to 1 mM ZnCl2 for 24 h in the presence of 11 mM glucose. Gene expression was normalized for β-actin, HSP, and Cltc. Data are shown as the mean ± SEM (n = 4–6). *P < 0.05.