PRKN and lip and oral cavity carcinoma: Interestingly, PRKN or PINK1 deficiency caused inhibition of both TOMM20 and COX4 degradation in MTFP1mLIR-overexpressing cells, but a decrease in TOMM20 level without affecting those of COX4 level was observed only in the MTFP1mLIR-expressing cells, confirming that PRKN is vital for degrading the outer mitochondrial membrane and not for mitophagy in CCCP-induced mitophagy in MTFP1-overexpressing oral cancer cells.