(a) Immunoblot analysis of proliferating cell nuclear antigen (PCNA), p-Rb, and p21Waf1/Cip1 expression in 16.5 dpc, newborn, and 5-day-old control ( + / + and inv/ + ) and inv/inv mouse kidneys. Signal intensity of PCNA, p-Rb, and p21Waf1/Cip1 was compared with that of corresponding actin expression. (b) Percentage of < 50 μm (open bars) and > 50 μm (black bars) renal tubules in 16.5 dpc, newborn, and 5-day-old wild-type and inv/inv mice. (c) Percentage of bromodeoxyuridine (BrdU)-incorporated cells per number of renal epithelial cells examined in 5-day-old kidneys. At least 200 tubules in each of three kidneys were examined. Each bar represents the mean ± s.e. *Significantly different from controls using Student’s t-test, with P < 0.05.