CHEK2 and breast cancer: Especially, the upregulated expressions of many genes of the top 5 signal pathways, such as CCNB1, CDC20, CDK1, CDC25C, CHEK2, MYBL2, E2F1, E2F2, and FOXM1 (Figure 3(c)), have been reported to be related to breast cancer occurrence [35–38], implying that the upregulated genes might be related to the more vigorous proliferation of tumors and stem cell as well as deterioration.