B16 cell proliferation is resistant to 19Arf gene transfer. (A) B16 (left) or C6 cells (right) were transduced with equal quantities of pCLPG (diamonds), pCLPGeGFP (squares) or pCLPGp19 (triangles) and replated for assessment of growth potential measured by counting cells each 24 hours during a 6 day period. Results presented are representative of three independent experiments. (B) B16 (left) or C6 cells (right) were transduced with equal quantities of pCLPG , pCLPGeGFP or pCLPGp19 and replated for the colony formation assay. The number of G418-resistant colonies counted in the pCLPG condition was considered as 1 and the colonies formed in the other conditions were normalized to this value. The results shown are the mean and standard deviation of three experiments.