Figure 5.
Stable binding of D-type cyclins with CDK4 enhances its nuclear localization, and CDK4/CDK6 knockdown results in cell-cycle arrest at the G1 phase. A, HeLa cells were transfected with GFP, GFP-p16, GFP-p21, or GFP-p27 for 24 h. The cell lysates were immunoprecipitated with anti-CDK4 antibody. The co-immunoprecipitated cyclin D1 was detected by Western blotting. B, HeLa cells transfected with GFP-tagged p16, p21, or p27 for 24 h were visualized by IFM. The DNA was stained with DAPI. More than 200 cells in each of three repeated experiments were randomly counted. Representative images are shown. C, HeLa cells were transfected with GFP or GFP-tagged p16 for 24 h. The nuclear and cytoplasmic extracts were analyzed by Western blotting. Scale bars, 10 μm.