FIG. 6.
Induction of p53 down regulates Bcl-3 protein levels in H1299w/tp53 cells. (A) p53 represses Bcl-3 but not p100/p52 protein levels. Following 16 h of p53 induction by increasing concentrations of IPTG in H1299w/tp53 cells, whole-cell lysates were prepared and the protein levels of p100/p52, Bcl-3, and β-actin control were analyzed by Western blot. (B) Bcl-3 down regulation is evident 12 h after IPTG induction of p53. p53 was induced in H1299w/tp53 cells by 100 μM IPTG. Cells were harvested at the indicated times following IPTG treatment, and nuclear protein extracts were prepared and analyzed by Western blot for Bcl-3 levels. (C) Induction of p53 in H1299w/tp53 cells does not repress Bcl-3 mRNA levels. RT-PCR analysis was performed by using two sets of primers specific to Bcl-3 (P1 and P2) or a GAPDH control, with total RNA prepared from H1299w/tp53 cells treated for 16 h with IPTG.