KMT2A and leukemia: At the endpoint no significant differences were observed between recipients of MLL-AF9 transformed WT or STAT3β-deficient cells in leukemia infiltration of the bone marrow (BM) and spleen (SP) (Supplementary Fig. 3B), blasts detected in the peripheral blood (Fig. 3C, Supplementary Fig. 3C), spleen size (Fig. 3D), or ex vivo proliferation (Supplementary Fig. 3D).