Mixed lineage leukemias(MLLs) are an evolutionarily conserved trithorax family of human genes that play critical roles in HOXgene regulation and embryonic well known to be rearranged in myeloid and lymphoid leukemias in children and adults. There are several MLL family proteins such as MLL1, MLL2, MLL3, MLL4, MLL5, Set1A and Set1B, and each possesses histone H3 lysine 4 (H3K4)-specific methyltrans-ferase activity and has critical roles in gene activation and epigenetics.