Both the citrate m+2/pyruvate m+3 ratio and the citrate m+4/citrate m+2 ratio were decreased in ccRCC mitochondria compared with those in kidney mitochondria (Fig. 2h), supporting the hypothesis that TCA cycle labelling reflects mitochondrial perturbations beyond simple PDH suppression. The gene discussed is PDP1; the disease is nonpapillary renal cell carcinoma.