FIGURE 5.

Cdc7 prevents Cdt2 from associating with Tob to suppress UV-induced apoptosis. A, puro/U2OS or TobF/U2OS cells transfected with the indicated siRNAs were irradiated with UV (30 J/m²). The cell lysates were analyzed using immunoblotting. The graph (lower) shows the percentages of apoptotic cells with condensed nuclei. Values are shown as the mean ± S.D. from triplicate experiments (**, p < 0.01). B and C, the interaction of TobF (B) or endogenous Tob (C) with endogenous Cdc7 and Cdt2 was analyzed using immunoprecipitation (IP) and subsequent immunoblotting. puro/U2OS, TobF/U2OS, or siRNA-transfected U2OS cells were used. The asterisks indicate heavy chain. The arrows indicate the positions of each protein. D, U2OS cells infected with control, TobF, or both TobF and His-Cdc7 expressing virus were lysed and subjected to IP analysis using anti-FLAG antibody. The lysates and anti-FLAG precipitates were analyzed by immunoblotting.