Furthermore, by knock-in of an MLL/AF9 gene into murine HPCs and human K562TRBSR cells, we validated that MLL/AF9 cells were highly susceptible to the anti-proliferative effects of metformin and the OXPHOS inhibitor; this was further supported by our ex vivo observation in MLL/AF9 blast cells from AML mice. The gene discussed is KMT2A; the disease is acute myeloid leukemia.