Figure 4
S. cerevisiae -viable tax mutants are attenuated in inducing cell cycle arrest/senescence in HeLa cells. HeLa cells transduced with a lentivirus vector carrying wild-type or mutant tax were selected in puromycin for 72 h as above and then grown in puromycin-free medium for 24 h. Cells in each group were then fixed in 70% ethanol, stained with propidium iodide, and analyzed by flow cytometry. (A) Flow cytometry chromatograms. (B) A bar graph representation of the fraction of cells in G1, S, G2/M phases of the cell cycle after transduction with tax alleles.