Figure 4. Medulloblastomas with Bax deletion are resistant to xRT despite activation of p53.

A,A’) Kaplan Meier curves compare the survival of radiated M-Smo;Bax^floxed mice to radiated and untreated M-Smo mice. Log Rank analysis shows that the difference in the survival of radiated mice with intact or deleted alleles of Bax is statistically significant. B–G) xRT induces γH2AX (B–D) and phosphorylation of p53 (E–G) in medulloblastomas of both M-Smo and M-Smo;Bax^floxed mice. H–M) IHC for cC3 demonstrates that apoptosis is strongly induced by xRT in M-Smo tumors, but greatly reduced in M-Smo;Bax^floxed tumors. N–P) TUNEL staining similarly demonstrates that cell death after xRT is greatly reduced in tumors with Bax deletion. Scale bars: 50 µm (B–-G and K–P), 100 µm (H–J).