Combine treatment of piceatannol and CDDP induces apoptosis in U2OS cells with additive effect. (A) U2OS cell were treated with piceatannol (40μΜ), and CDDP (20μg/ml) either alone or in combination for 24 h. The apoptosis rates were measured by staining the cells with Annexin V/PI using flow cytometry. (B) The protein levels of cleaved-caspase-3, cleaved-PARP, and ɣH2AX were determined using Western blot in U2OS cell. The bars in graph represent the relative density of the bands normalized to β-actin from three repeated experiments.