B-ALL development (22%; two out of nine) was observed in the generated Sca1-ETV6-RUNX1 + Kdm5cf/wt + Sca1-Cre mice born and kept in the SPF environment (n = 9; observed for up to 2 years) (Figure 5C and Supplementary Table 1). Here, ETV6 is linked to acute lymphoblastic leukemia.