Figure 3.

The effects of cucurbitacin E on the STAT3 phosphorylation, cell cycle-regulated associated proteins, and CDK1 activity in T24 cells. Cells at 1 × 10⁶ (cells/well) were placed in 6-well plates and then treated without and with 250, 500, and 1000 nM of cucurbitacin E for 24 h. Thereafter, cells were harvested and total proteins were collected for western blot analysis to examine the changes of protein levels of p-STAT, STAT, and p53 (a), p21, CDK1, and cyclin B1 (b) as well as CDK1 activity (c) as described in Materials and Methods. Each value is mean ± S.D. of three experiments; a, P ≤ 0.05, is significantly different compared with control (0 nM); b and c, P ≤ 0.05, reveal significantly difference compared with 250 and 500 nM of cucurbitacin E, respectively (one-way ANOVA followed by Bonferroni's test for multiple comparisons).