Survival curves of WT, Egr1-deficient, and Tp53-deficient mice after ENU treatment. (A,C) Kaplan-Meier survival curves of untreated and ENU-treated WT; Egr1^+/−; Tp53^+/−, and Egr1^+/−, Tp53^+/− mice. Percentage survival (time to euthanasia of moribund animals) is plotted vs time in days. The number of mice in each cohort is shown. Mice were bred on an Apc^fl/+Cre⁻ (Apc-WT) background. ENU-treated Egr1^+/− mice had a significantly decreased survival compared with ENU-treated WT mice (P = .02). The survival of ENU-treated Egr1^+/−, Tp53^+/− mice was significantly decreased as compared with ENU-treated Tp53^+/− mice (P = .03). The median survival for the Egr1^+/−, Tp53^+/− (505 days) and Tp53^+/− (510 days) untreated cohorts was not significantly different (P = .92). (B,D) Percentage of mice that developed an MPD with ineffective erythropoiesis or a T lymphoma/T-cell leukemia in non–ENU-treated and ENU-treated mice. P values were derived using Fisher’s exact test.