Phosphoglycerate kinase-1 (PGK1) is an instrumental ATP-generating glycolytic enzyme in the glycolytic pathway and overexpressed in many types of human cancer. However, the role of PGK1 in tumorigenesis and whether PGK1 has other important cellular functions in addition to its well established regulation in glycolysis remains obscure. Our preliminary data showed that hypoxia stimulation induced translocation of PGK1 into mitochondria. Importantly, mitochondrial PGK1 function as a protein kinase phosphorylates pyruvate dehydrogenase kinase 1 (PDK1). In additon, PGK1 depletion inhibits PDK1-regualted mitochondrial pyruvate metabolism and brain tumor growth in mice. We hypothesize that PGK1 coordinantly regulates glycolysis and mitochondrial metabolism in tumorigenesis. To test this hypothesis, we will pursue two specific aims: (1) To determine the mechanisms underlying mitochondrial translocation of PGK1; (2) To determine the role of PGK1- dependent PDK1 phosphorylation in tumor cell metabolism, cell proliferation, and tumorigenesis.