Figure 4.

CDC27 regulates p21 expression through modulating ID1 expression. (a) Real-time PCR, luciferase reporter assays (left) and western blotting (right) were performed to detect ID1 expression in the indicated cells with CDC27 was transiently overexpressed or suppressed. Mean±S.D. of triplicate samples are shown. **P<0.01, ***P<0.001 using Student's t-test. (b–d) Cells were harvested at 4 h after synchronization by serum starvation for p21 mRNA and protein expression level detection. Mean±S.D. of triplicate samples are shown. **P<0.01, ***P<0.001, Student's t-test. (e and f) ID1 was transiently overexpressed or suppressed in the indicated stable cell lines. Representative images of colony formation rescue assays and quantification were presented. Cells were subjected to cell cycle distribution analysis by flow cytometry. Mean±S.D. of triplicate samples are shown. *P<0.05, **P<0.01, ***P<0.001, Student's t-test