The degree of the per node was calculated by the Cytohubba plugin, and the top 5 degrees of DEGs are considered as the hub genes of BC, 12 up-regulated (FN1, AURKA, CCNB1, BUB1B, PRC1, TPX2, NUSAP1, TOP2A, KIF20A, KIF2C, RRM2, ASPM) and 1 down-regulated (PPARG) (Figure 3). The gene discussed is RRM2; the disease is breast cancer.