Figure 1.

Modified tet-inducible expression system. (A) Diagram of the modified tet-off system constructs. *Neo denotes a optimized Neo-resistance gene (18). (B) Induction of p53 in p53 wtA cells. Cells were induced by removing doxycycline for the indicated times and assayed by Western blot analysis for p53 and p21 expression. β-Catenin served as the loading control. (C) Inducible expression of p53 and p73 resulted in induction of p21, but mutant forms of p53 and p73 did not. A second clone expressing mutant p53 and p73 yielded results identical to those shown.