Effects of piceatannol on cell cycle control in LNCaP, DU145, and PC-3 CaP cells. Cells were treated with varying concentrations of piceatannol (0, 10, and 25 M) for 72 h and changes of cell cycle by piceatannol were further analyzed. (a) The effect on cell cycle distribution was analyzed by flow cytometry. The percentage of cells in G₁, S, and G₂M phases were calculated and values are expressed as mean ± SD. Cells with hypodiploid DNA content (sub-G₁) representing fractions undergoing apoptosis were also calculated. (b) Changes on the expression of various cell cycle regulatory proteins by piceatannol in LNCaP and PC-3 cells. Western blot analysis of cyclins D1 E and CDK6/CDK2 protein expression levels in total cell lysate treated with piceatannol for 72 h. (c) Effects of piceatannol treatment on apoptosis-associated proteins in DU145 cells. Changes in expression of PARP, caspase 3, cytochrome C, and AIF were further analyzed by western blot analysis. (d) Effects of piceatannol on DNA-damage-associated changes in DU145 cells were further analyzed by determining the changes in the expression of phosphorylated H2AX using western blot analysis. Actin expression was used as a loading control. The intensity of the specific immunoreactive bands was quantified by densitometry and expressed as a fold difference against actin.