Survival analysis of six hub genes in ccRCC (based on TCGA data in GEPIA). (A) Overall survival analysis. (a) CCNB2, (b) CDC20, (c) CEP55, (d) KIF20A, (e) TOP2A, and (f) UBE2C. (B) Disease free survival analysis. (a) CCNB2, (b) CDC20, (c) CEP55, (d) KIF20A, (e) TOP2A, and (f) UBE2C. Red line represented the samples with gene highly expressed and blue line was for the samples with gene lowly expressed. HR: hazard ratio. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)