Pyruvate carboxylase (PC, 40-fold), which transfers a carboxyl group to pyruvate to form oxaloacetate (OAA) and phosphoenol pyruvate carboxykinase (PCK1, 5-fold and PCK2, 9-fold), which catalyze the conversion of OAA to phosphoenolpyruvate (PEP), the rate-limiting step in the metabolic pathway that produces glucose from lactate were two of the most decreased enzymes abundant in renal oncocytomas. Here, PCK2 is linked to kidney oncocytoma.