Figure 5.

c-Abl expression stimulates colony formation of c-Abl−/− p53−/− cells. (A) Cells were plated at low density (3.5 × 10³ cells per 10-cm plate) and cultured for 8 days. The number of visible colonies per plate after staining with crystal violet is shown for each genotype. (B) p53−/− and c-Abl−/− p53−/− cells were infected with retrovirus encoding neomycin vector only, wild-type (wt) c-Abl, or kinase-inactive c-Abl K290R (KR) mutant. Cells were plated 2 days after infection, and colony formation was determined as described above. (C) Analysis of c-Abl expression. Cell lysates prepared at the time of plating for colony formation after retrovirus infection were immunoblotted with anti-c-Abl monoclonal antibody. c-Abl−/− p53−/− cells lack endogenous c-Abl expression, consistent with their genotype.