PDK1 and nonpapillary renal cell carcinoma: Pyruvate dehydrogenase kinase, isoenzyme 1 (PDK1, Gene ID: 5163; mRNA increased 7.5-fold in TRACK kidneys and nearly 5-fold in ccRCC) phosphorylates and inactivates pyruvate dehydrogenase, an enzyme that converts pyruvate to acetyl-coenzyme A. Thus, PDK1 inhibits pyruvate metabolism via the TCA cycle and in turn inhibits oxidative phosphorylation [37].