OXPHOS was the most activated pathway in ovarian tumor cells compared with the non-tumor tissues, in which 29 proteins related to OXPHOS were significantly upregulated in OC, including 11 subunits of mitochondrial respiratory complex I, nine subunits of mitochondrial ATP synthase, six subunits of mitochondrial cytochrome c oxidase, CYC1, CYCS, and UQCRH (Fig. 1C). Here, CYCS is linked to ovarian neoplasm.