HOXA9 and leukemia: Leukemia of different genetic backgrounds was derived either from transgenic mouse models (Flt3ITDIDH2R140Q, BCR/ABL, and p53−/− leukemic cells27,28) or through transduction of HSCs with retroviral vectors (HoxA9–Meis1 and MLL/AF9 leukemic cells) (Supplementary Fig. 3b).