(a) Immunohistochemical analysis of Pdx1 expression in β cells of wild-type, Irs2^–/–, and Irs2^–/–Foxo1^+/– mice. We costained pancreatic sections with anti-Pdx1 (green) and anti-insulin antibodies (red). We show a representative section. (b) Subcellular localization of Foxo1 in Pdx1-positive and Pdx1-negative β cells from wild-type mice. We double-stained adjacent pancreatic sections from 2-week-old mice with antisera against insulin (red) and Pdx1 (mauve pseudocolor), or insulin (red) and Foxo1 (green). We acquired images using a SPOT-RT digital camera and overlaid them using the insulin-stained sections to match the position of the same nucleus in the two sections. Thereafter, we analyzed the colocalization of Pdx1 and Foxo1. We show a ×60 magnification. In the schematic diagram, an empty circle indicates an overlapping nucleus in the two sections. These nuclei have been numbered to facilitate identification of matching cells in the two sections. A mauve nucleus indicates exclusive Pdx1 immunoreactivity; a green nucleus, exclusive Foxo1 immunoreactivity.