Gadd45a inactivation extended survival from brain tumors in IR treated TgT121 mice. (A) Survival of TgT121;gadd45a+/+ mice and TgT121;gadd45a−/− mice without IR treatment. Kaplan Meier curves showed a shorter survival of TgT121;gadd45a−/− mice (t50 =207 days, n=45) than TgT121;gadd45a+/+ mice (t50=263 days n=60). (p<0.05, log-rank test). (B) After sub-lethal IR treatment to the head (see Methods), TgT121; gadd45a−/− mice had a better survival (t50=285 days, n=7) than TgT121; gadd45a+/+ mice (t50=223days, n=18) (log rank test, p<0.05).