NME1 and carcinoma: According to the current studies, NM23 maybe play a role via inhibiting the activities of important signaling pathways, which are necessary in the process of tumor invasion, such as Ras/mitogen-activited protein kinase and transforming growth factor-β,[9,16] inhibiting the expression of matrix metalloproteinase-2 and suppressing the cloning ability of carcinoma cells.[17,18] Thus, some authors thought that altered expression of NM23 is related to tumor invasion and metastasis.