PDX-1 expression and insulin secretion of islets of E2F1^_/_ and E2F1^+/+ mice. (A) In situ hybridization of E2F1 or PDX-1 in sections of 12.5 or 16.5 dpc embryos. Location of liver (liv), stomach, skin, lung, pancreas (panc), intestine (int), and dorsal root ganglion (rg) in the embryo is indicated. (B) Immunofluorescence analysis of PDX-1 expression (green) in insulin-producing cells (red) of pancreatic sections of E2F1^+/+ or E2F1^_/_ 16-week-old mice. (C) Quantification (500 cells) of insulin-producing cells, which also expressed PDX-1. Results are relative to total number of insulin-producing cells. (D) Cellular localization of PDX-1 expression (green) in pancreatic β cells. Hoechst staining of nuclei is in blue. (E) Quantification of the expression by real-time RT-PCR of relevant genes for pancreatic islet development or function. Results were normalized by the expression of the 18S ribosomal subunit RNA. (F) Insulin secretion of isolated islets of E2F1^+/+ or E2F1^_/_ mice in the absence or presence of 5, 10, or 15 mM glucose. Islets were isolated from 16-week-old male mice. Results are relative to total DNA and insulin content. tot ins, total insulin.