Overexpression of gankyrin reduces pRB levels and makes Lmna^+/+ cells refractory to p16^ink4a-induced arrest.

(A) Western analysis of Lmna^+/+ infected with a control plasmid, Lmna^+/+-Cont, or gankyrin, Lmna^+/+-Gank, and uninfected Lmna^−/− fibroblasts. Rb^−/− fibroblasts were included as a control for pRB levels. (B) Cells were transfected with GFP-p16^ink4a or GFP-p21^cip1 and GFP-positive cells were scored; S-phase cells were identified by BrdU incorporation. The percentage of cells positive for GFP and BrdU incorporation were quantified. Results are shown with standard deviations from triplicate samples; 150 cells were counted per sample. (C) Flow cytometry was conducted on Lmna^+/+-Cont and Lmna^+/+-Gank cells transfected with GFP or GFP-p16^ink4a.