NM23 is a heterodimeric protein functioning as a nucleoside diphosphate (NDP) kinase. NME1 and NME2 comprise the 152 amino acid A and B polypeptide chains of the NM23 enzyme, respectively. NME2 is identical to the beta subunit of human erythrocyte NDP kinase. NDP kinases are involved in the synthesis of nucleoside triphosphates, and NM23 may act in the regulation of signal transduction by complexing with G proteins, causing activation/inactivation of developmental pathways. NEM2 has been ide