PBX3 exhibited a synergistic effect with HOXA9 in inducing leukemia in transplanted mice. (A) The PBX3⁺HOXA9 (ie, MSCV-PIG-PBX3⁺MSCVneo-HOXA9; n = 6) group developed leukemia significantly faster (median overall survival, 71 days versus 140 days; P < .0001, log-rank test) than the HOXA9 alone (ie, MSCV-PIG⁺MSCVneo-HOXA9; n = 6) group, whereas the control group (ie, MSCV-PIG⁺MSCVneo; n = 6) and the PBX3 alone (ie, MSCV-PIG-PBX3⁺MSCVneo; n = 7) group did not develop leukemia. Kaplan-Meier curves are shown. (B) Flow cytometric analysis of BM cells of representative mice stained with APC-labeled anti-CD117 (ie, c-Kit) antibody and eFluor 450–labeled anti-CD11b (ie, Mac-1) antibody. (C) Comparison of cell morphology between the 4 mouse groups. Peripheral blood (PB) and BM cell cytospin via Wright-Giemsa staining are shown.