Analysis of cell cycle phase-specific proteins in wild-type and β2SP+/− mouse livers following partial hepatectomy. (A) Immunohistochemical analysis of pRb (Ser249/Thr252), PCNA, and p-histone (Ser10) demonstrated increased pRb and PCNA labeling in β2SP+/− mice at 24 hours; however, p-histone labeling was absent in β2SP+/− mice at 48 hours after hepatectomy. (B) Western blot analysis demonstrated significantly elevated pRb and cyclin D1 expressions in mutant mice at 24 hours and diminished expressions of cyclin E, cyclin A, cyclinB1 and Cdk1, especially at 48 hours. (*P<0.05)