KMT2A and leukemia: In an effort to identify the cell-of-origin of MLL-AF9-associated AMLs, Lavau et al., Cozzio et al., Krivtsov et al. [49,50,51], and Somervaille and Cleary [52] used retroviral vectors to transduce different murine hematopoietic progenitors with MLL fusion oncogenes and reported that both bona fide hematopoietic stem cells, as well as committed (common myeloid and granulo-monocytic) progenitors could be transformed by MLL-ELL, MLL-ENL, and MLL-AF9 into cells with leukemia-initiating properties.