1 ONCOGENIC KMT2A-COMPLEXES IN LEUKEMIA In mammalian cells six members of the Mixed-Lineage Leukemia (MLL)-family (MLL1/KMT2A, MLL2/KMT2B, MLL3/KMT2C, MLL4/KMT2D, SETD1A/KMT2F and SETD1B/KMT2G) encode for methyltransferases that catalyze Histone 3 lysine 4 mono-, di- and tri-methylation (H3K4me1/2/3) at promotors and enhancer regions and influence transcription.