Glutamine induction of insulin secretion. MIN6 cells were treated as in Fig. 1, and insulin levels were determined by radioimmunoassay. A, amounts (ng) of insulin in each condition. B, secreted insulin expressed as percent of intracellular content. The data are the means ± S.D. from three independent experiments.*, p < 0.05; **, p < 0.01; ***, p < 0.001.