Except for the in-depth insight into the biological functions of the above-mentioned four CRGs, 19 other identified CRGs involved in the signature, namely, ANAPC4, MMAB, B9D2, NDEL1, SLC25A15, PSMA7, PSMB10, PSMB5, PSMB8, RAD9A, REXO2, ARID3A, CHMP4C, DDX39B, FBXO31, FBXO6, PRPF19, RGCC, and TIPIN, were first identified to play a potential role in BC progression, and their detailed functions remained enigmatic, which merited further experimental verification. This evidence concerns the gene REXO2 and breast cancer.