Also known as ATP:3-phosphoglycerate 1-phosphotransferase (EC 2.7.2.3), this major enzyme in glycolysis catalyzes the reversible conversion of 1,3-diphosphoglycerate to 3-phosphoglycerate, generating one molecule of ATP. New blood vessel formation or angiogenesis is critical for tumor expansion and metastasis. Lay et al. (2000) showed that the plasmin reductase isolated from conditioned medium of fibrosarcoma cells is the glycolytic enzyme phosphoglycerate kinase. They concluded that phosphoglycerate kinase not only functions in glycolysis but is secreted by tumor cells and participates in the angiogenic process as a disulfide reductase.