RUNX1 and lymphoid leukemia: ETV6-ETV6–RUNX1 + Sca1-Cre mice had a shorter lifespan when exposed to natural infections than their WT littermates [Figure 2A; p < 0.0001; log-rank (Mantel–Cox) test; Supplementary Table 1] due to the development of specific lymphoid leukemias, including both T- (34.4%; 11/32) between 6.2 and 14.2 months of age and B-ALL (6.3%; 2/32) between 19.5 and 20.1 months of age.