Whole-exome sequencing of Sca1-ETV6-RUNX1 + Kdm5cf/wt + Sca1-Cre B-ALL (n = 2; Figure 4) showed an overlap with genes or pathways mutated in B-ALL and an absence of T-ALL-specific mutations, such as Notch1. Our data, therefore, indicated that second molecular alterations may confer cell identity to ETV6-RUNX1+ leukemia. The gene discussed is RUNX1; the disease is acute lymphoblastic leukemia.