Figure 2: Immunostaining for insulin and glucagon. Immunolocalization of islets for β-cell marker insulin (green) and α-cell marker glucagon (red), counterstained with 4′,6-diamidino-2-phenylindole (DAPI) (nuclear stain) (blue), showed increased insulin immunostaining among Mutants compared to Lean and Control and with age from 1 month (a) to 6 months (b) and 12 months (c) and showed a comparison with 24-month-old (2 yr) Controls (d). Isotype control is also represented (e). Quantitative fluorescence measurements as relative fluorescence units (RFU) for (f) insulin, (g) glucagon, (h) insulin to glucagon ratio, and (i) β-cell mass were calculated from insulin stained areas. An asterisk (*) represents significance ( by ANOVA) compared to Control and ($) indicates significance ( by ANOVA) compared to the same phenotype at 1 month.