AFF1 and leukemia: Enrichment of the Myc and Myb signatures was also observed in mouse leukemias with de novo Kras/Ptpn11 mutations (MAF 0.39–0.59) and in primary infant KMT2A-AFF1 ALL harboring activating mutations4 (Fig. 4f, Supplementary Fig. 9g-j, and Supplementary Data 27, 28).