We also reported that extracellular NM23 could inhibit the erythroid differentiation of human leukemia cell lines (K562, HEL, and KU812) without any effect on proliferation [47] and that serum NM23-H1 levels in AML-M6 (acute erythroleukemia classified by FAB (French-American-British) classification) were especially high and significantly higher than that in other FAB subtypes of AML [32]. This evidence concerns the gene NME1 and leukemia.