a, b Effects of 24 h incubation with different concentrations of F1-7 on cell cycle. With the increase of F1-7 concentration, cells were arrested in the G2/M phase. Data are expressed as mean ± SD (n = 3). c Cells were incubated with F1-7 at different concentrations as indicated for 24 h, the cell lysates were prepared for western blot analysis to determine protein expression of CyclinB1, MDM2, CDK1 and GAPDH.