KMT2A and leukemia: Dimerization of MLL N-terminal portion of MLL gene converts it into a transcriptional transactivator, leading to upregulation of HOX proteins, especially HOXA9 and MEIS1, that are overexpressed in a wide variety of some leukemias (T-ALLs, acute myeloid leukemia and biphenotypic leukemia) and that act, at least partially, through activation of the proto-oncogene MYB [24].