Interestingly, CI-deficient masses were composed of eosinophilic cancer cells (Fig. 1d) harboring swollen mitochondria with deranged cristae (Fig. 1e, Supplementary Fig. 3c), well recapitulating oncocytic lesions, which was further strengthened by the finding that 143B−/− xenografts displayed an increased expression of PPARGC1A, the master regulator of mitochondrial biogenesis (Supplementary Fig. 3d). Here, PPARGC1A is linked to cancer.