KMT2A and acute leukemia: Menin (MEN1) is a well-recognized powerful tumor promoter in acute leukemias (ALs) with lysine methyltransferase 2A (KMT2A, previously known as MLL: mixed-lineage leukemia) rearrangements (KMT2Ar) and mutant nucleophosmin 1 (NPM1m) [1,2,3].