We were motivated to examine the non-histone PKMT activity of EZH1 in AML1-ETO leukemia, because: (1) EZH1 appears in the AML1-ETO complex; (2) EZH1 and AML1-ETO have a direct protein–protein interaction; (3) EZH1 has a SET domain carrying PMKT activity26; (4) EZH1 displays contrasting activity against EZH2 and possesses weaker HMKT activity compared to that of EZH225; and (5) EZH1 appears to have PRC2 complex-independent functions. This evidence concerns the gene EZH2 and leukemia.