Figure 6.

The outcome of E2F1 overexpression in Saos2 cells is mediated by DDR activation. A: Apoptotic rate in the Saos2 E2F1-ERsiATM, Saos2 E2F1-ERsip73, and Saos2 E2F1-ERshp14^ARF cells before and after the addition of 4-OH-Tamoxifen (4-OH-Tam), respectively. The lines are the means of three independent experiments. Immunoblots for ATM, p73, and p14^ARF confirmed corresponding gene silencing. B: Western blot analysis of γH2AX, Chk2-pT68, Chk2, and p73. Actin serves as loading control. C: Immunofluorescence analysis in Saos E2F1-ER cells showing the presence of H2AX foci before and after addition of 4-OH-Tamoxifen. D: Western blot analysis for p73 expression in Saos2 E2F1-ER cells treated with 4-OH-Tamoxifen and silenced for ATM expression.