This was reflected in primary ccRCC cells in culture by a very low basal OCR as measured by the Seahorse technique, low mitochondrial DNA content and a correspondingly high tolerance to inhibitors of mitochondrial respiration at concentrations shown to be lethal to other tumor cells in culture.14, 15, 16 The low mitochondrial content results in a limited ability of primary ccRCC cells to increase OCR and flux through the electron transport chain after uncoupling of the mitochondrial ATPase, illustrated by addition of the uncoupler FCCP in the Seahorse assay. The gene discussed is ATP5F1E; the disease is nonpapillary renal cell carcinoma.