CCNA2 and nonpapillary renal cell carcinoma: After PPI analysis, 22 hub genes related to ccRCC stood out, among which CD4, PTPRC, CCNA2, CD8A, BUB1, ASPM, BUB1B, KIF20A, CENPF, DLGAP5, ITGB2, KIF2C, TYROBP, BIRC5, CEP55, ITGAM, MELK, NUSAP1, and TPX2 were found to differentially methylated genes between ccRCC tissues and paired tumor-free kidney tissues.