MEIS1 and acute myeloid leukemia: A key characteristic of NPM1c+ in AML patients is the high expressions of the homeobox (HOX) transcription factors (TFs), including the HOXA/B cluster genes, MEIS1 (myeloid ecotropic viral integration site 1) and PBX3 (pre-B-cell leukemia homeobox 3) [48].