NME1 and neoplasm: The disruption of CD39 (ecto-apyrase; EC 3.6.1.5) activity, the dominant vascular ecto-nucleotidase, and its regulation of nucleotide signaling has been observed to inhibit tumor angiogenesis and metastasis [76,77] consistent with, if not directly demonstrative of a role for secreted NM23/NDPK in promoting angiogenesis.