12 upregulated hub genes (TOP2A, MAD2L1, FEN1, EPRS, EXO1, MCM4, PTTG1, RRM2, PSMD14, CDKN3, H2AFZ, CCNE2) identified from GSE database were confirmed to be high expression genes in breast cancer (Fig. 2 and 3) (p<0.05) and 4 downregulated hub genes (EGFR, FGF2, BCL2, PIK3R1) confirmed to be low expression genes (Fig. 4) (p<0.05). This evidence concerns the gene RRM2 and breast cancer.