Unexpectedly, all analyzed murine leukemias (n = 12) showed normal karyotypes (Fig. 2e; Supplementary Fig. 9; Supplementary Table 1), indicating that p53 haploinsufficiency or loss per se does not lead to genetic instability, and genetic instability is not a major cause for AML and ALL development by the co-occurrence of p53KO and FLT3-ITD. This evidence concerns the gene FLT3 and leukemia.