Roles of Bcl-2 family members in inhibiting cell death after cisplatin treatment of cell lines derived from HNSCC. A, diagram summarizing how genotoxic therapy such as chemoradiation affects the p53 family members p63 and p73 in HNSCC, and the downstream inhibition of p73-induced apoptosis by antiapoptotic members of the Bcl-2 family. B through D, scatter plots of cisplatin IC50 versus endogenous mRNA levels of Bcl-2 family members for 19 cell lines derived from HNSCC. Logarithmic horizontal axis allows display of cell lines differing by several orders of magnitude in expression. Regression lines of IC50 against logarithm of mRNA level are plotted, along with correlation coefficients and significance. B, Bcl-2; C, Bcl-XL; D, Bcl-w. Bcl-2 mRNA levels displayed in this figure were highly correlated with protein expression seen on Western blots; cf. Supplementary Fig. S3.