KDR and neoplasm: Our more recent examination of the mechanisms of the P2Y1 receptor pathway with regard to transactivation of VEGFR-2 Tyr1175, extracellular signal-related kinase (Erk1/2) activation, and functional determination of cell growth and migration, reinforce the biology of the extracellular actions of NM23/NDPK in support of tumor angiogenesis [78].