Pancreatic knockout of Grb10 increases pancreas weight, β-cell mass, and BrdU incorporation rate in β-cells. A: Mouse tissues were isolated from 5-month-old male WT (n = 6) and pGrb10KO mice (n = 5) fed with normal diet and weighed by electronic balance. B: β-Cell size between male pGrb10KO mice and WT littermates (n = 4/group; >500 cells were counted per slide) was measured using Image-Pro Plus software (Version 5.0; Media Cybernetics,
Inc). C: Average β-cell mass between 5-month-old male pGrb10KO mice and WT littermates fed with normal diet (WT: n = 7; pGrb10 KO: n = 4). D: Knockout of Grb10 increased β-cell proliferation as determined by BrdU cell proliferation assay. BrdU was injected into
2-month-old male mice (100 mg/kg), and mice were killed 16 h after injection. More than 2,500 insulin-positive cell nuclei
were counted per mouse under a Nikon TE2000 microscope (Nikon; WT: n = 3; pGrb10KO: n = 4). Black bars, Grb10 flox+/−; white bars, pGrb10 KO. All data represent mean ± SEM. *P < 0.05; **P < 0.01 (t test).