Loss of endogenous Bcl-2 does not delay Eμ-myc–induced B lymphoma development. Kaplan-Meier analysis of tumor latency in lethally irradiated wt (Ly5.1⁺) mice reconstituted with fetal liver cells from Ly5.2⁺ Eμ-myc (■) and Eμ-myc/bcl-2^−/− (□) (E14.5) embryos. Mice were killed when deemed moribund by an animal technician who was blinded to the genotype of the mice. Cause of death was classified as Eμ-myc lymphoma according to the criteria detailed in “Materials and methods.”