PAX5 and precursor B-cell acute lymphoblastic leukemia: Double Sca1-ETV6-RUNX1 + Pax5-het mice developed B-ALL (62.5%; five out of eight); as a result, they had shorter lifespans than their WT, Pax5-het, and Sca1-ETV6-RUNX1 littermates [Figure 6A; p < 0.0001; log-rank (Mantel–Cox) test] when kept in an SPF environment.