Ionizing radiation-induced accumulation of p53, p21, MDM2, and TRAIL-R2 at 0 hours and 10 hours following IR in

ATM mutant B-CLLs. B-CLLs 34, 33, 7, 1, and 35 are representative of 8 tumors with ATM mutations showing defective p53, p21, and MDM2 responses following exposure to IR. B-CLLs 38 and 39 are ATM mutant tumors with normal p53 accumulation but defective p21 and MDM2 up-regulation. A B-CLL tumor (B-CLL 9) withTP53 mutation showed an elevated basal p53 protein level but a defect in the ability to accumulate p53 and up-regulate p21 and MDM2. B-CLLs 20, 52, 19, 50, and 13 are representative of 19 analyzed tumors with wild-type ATM and p53 which showed normal p53, p21, and MDM2 responses. The TRAIL-R2 response 10 hours after irradiation was defective in ATM-deficient tumors (B-CLLs 34, 33, 1, 38, 39, 7, and 35) as well as in TP53 mutant (Mut) B-CLL 9, but it was normal in B-CLLs 20, 52, 19, 50, and 13 representative of 12 B-CLLs withATM/TP53 wild type (WT) analyzed for TRAIL-R2 response. The actin expression shows equal loading.