Piceatannol induces G2/M phase arrest in U2OS cells. (A) U2OS cells were treated with various concentrations of Piceatannol for 24 h. Flow cytometry was used to assess cell cycle profile. (B) U2OS cells were treated with Piceatannol for 24 h. The expression of cell cycle regulators was analyzed by Western blotting. The bars in graph represent the relative density of the bands normalized to GAPDH from three repeated experiments.