Immunohistochemistry staining for p21 and PCNA in the remaining liver after PH. (A) p21 staining. There are more p21 positive hepatocytes in the liver tissue sections from WT mice compared to KO mice at 6 or 24 hours after PH. (B) PCNA staining. There were fewer PCNA positive cells in the liver tissue sections from WT mice compared to KO mice at 24 hours after PH. p21 or PCNA positive hepatocytes in each slide were counted in five low-power (×100) fields. Data represent mean ± SEM (n = 3). *P < 0.01.