FIGURE 1.

Increased insulin secretion despite normal insulin content and β cell mass after LKB1 loss. A, glucose tolerance test in old βLKB mice. Mice were injected with tamoxifen at 1 month of age, and assays were performed 16 months later. n = 4 or 5 per genotype. p value <0.05 by repeated measures analysis of variance. B, plasma insulin levels in old βLKB mice, 15 min after glucose injection. Error bars represent S.D. Mice were injected with tamoxifen at 1 month of age, and assay was performed 1 year later. n = 3 per genotype. C, β cell mass. Graphs represent the percentage of pancreas tissue area stained for insulin (left), the fraction of insulin-stained tissue multiplied by pancreas weight (total β cell mass in mg; center), and total β cell mass per body weight (right). Mice were 4 months old, 3 months after tamoxifen injection. n = 3 mice per group. D, insulin content in pancreata from fed and fasted lox/lox littermate controls and βLKB mice. Insulin content is presented relative to pancreas weight. βLKB mice do not differ in their pancreatic insulin content in either fed or fasted states. n = 4–7 mice per group. E, dynamic insulin secretion assay. Data represent the mean of data from 5 mice per group at age of 6–8 months. For each sample, measured insulin was normalized to total DNA. *, p < 0.05; **, p < 0.01; ***, p < 0.005; ns, p > 0.05.