Acute Men1 excision ameliorates hyperglycemia in db/db mice. (A) A schematic of experimental design. Control db/db;Men1l/l and db/db;Men1l/l;Cre-ER mice (n = 5–7 mice) were fed TAM at the age of 6 wk. Mice were killed 8 wk after TAM feeding. (B and C) Immunostaining for menin and insulin in islets from control mice (B) and db/db;Men1l/l;Cre-ER mice (C) 8 wk after TAM treatment. (Scale bar, 25 μm.) (D and E) Glucose tolerance test (GTT, glucose at 2 g/kg of body weight, i.p.) before (D) and 8 wk after (E) TAM treatment. (F–I) BrdU incorporation by β cells. (F and G) Immunostaining for BrdU and DAPI. (H and I) Immunostaining for BrdU and insulin. (Scale bar: 25 μm.) (J) Quantitation of BrdU incorporation by β cells. (K) Quantitation of insulin-staining area. (L) Glucose-stimulated insulin secretion (GSIS, glucose at 3 g/kg of body weight, i.p.), measured 8 wk after TAM treatment. *P < 0.05; **P < 0.01.