Mini–gene expression analysis indicating increased prosurvival pathway signaling in apoptosis-resistant ALL tumors. (A) Cluster analysis of the difference in expression of apoptotic genes before and 8 hours after 5 Gy IR comparing apoptosis-proficient and apoptosis-resistant tumors. Three patterns of gene expression were observed. (B) Western blot analyses showing defective expression of TRAF5, TRAF6, and cIAP1 proteins in apoptosis-resistant ALL tumors compared with apoptosis-proficient ALL tumors and the p53 mutant leukemia, ALL 19, 8 hours after IR. Actin serves as a loading control. (Underlined ALL tumors were not previously analyzed by array expression analysis.)