CCNA2 and CCNB1 were tightly linked to each other and co-expressed with several genes in common, including CCNB2, CDK1, BUB1, NEK2, and CENPA. The four cyclin genes were closely connected with cell cycle-relevant genes (CDK1, CDC25C, CDC25A, and CDC20; Figures 11B–E), as well as mTOR-related gene (RRM2) and cancer-related genes (BIRC5, BCL2L12, and PLK1; Figures 11F–I). This evidence concerns the gene PLK1 and cancer.