P53 promoted DOX-induced cell death was partly due to its ability to stop cell cycle progression. Cells were transiently transfected with or without over-expression of p53 alone or p53 and p65 together followed by DOX treatment (2 μg/ml) for 24 h. (A) The level of CDK2, CDK4, cyclinD1 or cyclinE protein were detected by Western blotting. GAPDH was used as controls. (B) Cell cycle pattern. Error bar indicates the standard error of the mean of three independent experiments.