FIG. 2.
Characterization of ALT-positive HIO107 or telomerase-positive HIO114 cell lines expressing either wild-type (WT) or transactivation-incompetent (TA) p53. (A) Western blot analysis of whole-cell extracts from the indicated cell lines prepared after 48 h of growth at 39 or 32°C probed to detect p53, p21WAF1, and T-Ag as a loading control. p53-TA does not result in accumulation of p21WAF1 protein. P, parental cell line. (B) Frequency of apoptotic cells, detected by 7 AAD and annexin V staining, in the indicated cell lines. Results are shown as the increase (n-fold) in apoptosis when cells are cultured at 32°C compared to the level of background apoptosis in the culture at 39°C. Relative to ts-p53WT, the ts-p53TA allele is impaired in its ability to induce apoptosis at the permissive temperature of 32°C. (C) Growth curves of the HIO107 ALT (squares) or HIO114 telomerase-positive (circles) derived cell lines at 39°C (open symbols; solid line) or 32°C (filled symbols; dashed line). Expression of p53-TA causes growth inhibition in the HIO107 ALT background. The results are the summary of experiments done in triplicate. Where they are not visible, the standard error bars are below the resolution of the graph.