NME1, also known as Nucleoside Diphosphate Kinase A (NDK-A), or NM23-H1, belongs to the NDK family. NM23-H1 is known to have a metastasis suppressive activity in many tumor cells. Recent studies have shown that the interacting proteins with NM23-H1 which mediate cell proliferation, may act as modulators of the metastasis suppressor activity. The interacting proteins with NM23-H1 can be classified into 3 groups. The first group of proteins can be classified as upstream kinases of NM23-H1 such as CKI and Aurora-A/STK15. The second group of proteins acts as downstream effectors for the regulation of specific gene transcriptions, GTP-binding protein functions, and signal transduction in the Erk signal cascade. The third group of proteins can be classified as bi-directionally influencing binding partners of NM23-H1. As a result, the interactions with NM23-H1 and binding partners have implications in the biochemical characterization involved in metastasis and tumorigenesis. NDKA is increased in human postmortem cerebrospinal fluid (CSF), a model of global brain insult, suggesting that measurement in CSF and, more importantly, in plasma may be useful as a biomarker of stroke. Additionally, NM23-H1 significantly reduces metastasis without effects on primary tumor size and was the first discovered metastasis suppressor gene.