Deletion of Ldb1 in endocrine hormone+ cells causes reduced pancreatic hormone production, postnatal islet loss, and hyperglycemia in vivo. A: Six-hour fasting blood glucose levels in littermate control and Pax6-Cre;Ldb1F/F pups. Horizontal bars indicate mean blood glucose values within each genotype, and values were significantly different between control and mutants at all ages (P < 0.0001). Insulin (brown) and eosin (pink) staining at P6 and P21 in the control (B and C) and Pax6-Cre;Ldb1F/F (D and E) pancreas. F: Islet hormone insulin, glucagon, and somatostatin (SST) mRNA levels are significantly reduced in E18.5 Ldb1 mutant pancreata (n = 4–6). Data are presented relative to littermate controls, which are set at onefold and marked by the dashed line. Error bars represent ± SEM. The number of pancreatic insulin+ (green), glucagon+ (red), and somatostatin+ (white) cells is greatly reduced between E18.5 control (G and H) and Pax6-Cre;Ldb1F/F (I and J) tissue. The insets in H and J show a magnified view of the cell clusters. *P < 0.05. (A high-quality digital representation of this figure is available in the online issue.)