FIG. 2.

p53 selectively down regulates cyclin D1 expression. (A) Induction of p53 in H1299^w/tp53 cells represses cyclin D1 protein in a dose-dependent manner. Whole-cell lysates from H1299^w/tp53 cells, treated for 16 h with increasing concentrations of IPTG, were subjected to Western blot analysis by using antibodies to cyclins A, B1, D1, E, and a β-actin control as indicated. (B) Induction of p53 in H1299^w/tp53 cells represses cyclin D1 mRNA levels. RT-PCR analysis was performed by using primers specific to cyclin D1 or a GAPDH control, with total RNA prepared from H1299^w/tp53 cells treated for 16 h with IPTG.