FIG. 6.

The active Rac1, RhoA, and Cdc42 mutants cooperate with p19Arf or p53 deletion to promote cell transformation. (A) Expression of the constitutively active mutants of Rac1, RhoA, and Cdc42 containing an N-terminal HA tag in p19Arf- or p53-null cells was probed by anti-HA Western blotting. (B) Five thousand MEF cells expressing the indicated proteins were mixed with 5 × 10⁴ parental p19Arf^−/− or p53^−/− cells and cultured in 100-mm plates. The cell cultures were fed every 2 days with fresh culture medium. Fourteen days postplating, the foci were fixed, stained, and quantified under a microscope. The data are representative of two independent experiments. WT, wild type.