Piceatannol effectively induces apoptosis and suppresses PI3K/AKT pathway in U2OS cells. (A) Cells were stained with Annexin V/PI and apoptosis was determined by flow cytometry. (B) U2OS cells were treated with different concentrations of piceatannol for 24 h and expression of apoptosis regulating proteins was measured by Western blotting. (C) The inhibitory effect of piceatannol on PI3K/AKT pathway was assessed by Western blot. The bars in graph (B & C) represent the relative density of the bands normalized to GAPDH from three repeated experiments.