Egr1 haploinsufficiency alters the disease phenotype in Tp53^−/−and Tp53^+/−mice. (A,C) Kaplan-Meier survival curve of Tp53^−/− and Tp53^+/− mice crossed with Egr1 WT or Egr1^+/− mice. Percent survival (time to euthanasia of moribund animals) is plotted vs time in days. The number of mice in each cohort is shown. Egr1^+/−, Tp53^−/− mice had a significantly decreased survival compared with Tp53^−/− mice (P = .002). The median survival for Egr1^+/−, Tp53^+/−, and Tp53^+/− mice was not significantly different (P = .29). (B,D) Distribution of diseases developing in the mouse cohorts. All Tp53^−/− crosses became moribund in <300 days. The study was terminated at ∼600 days for mice crossed on the Tp53^+/− background. (B) “Other” includes 2 Tp53^−/− mice that were euthanized due to a reactive condition. (D) “Other” includes 1 Tp53^+/− mice that was euthanized due to severe dermatitis; 1 Tp53^+/− and 1 Egr1^+/−, Tp53^+/− mouse that developed intestinal complications. “Osteosarcoma” includes 2 Egr1^+/−, Tp53^+/− mice that developed hind leg paralysis, a common symptom of osteosarcomas. P values are from a Fisher’s exact test, comparing the frequency of disease type between genotypes.