In line with this, it was reported that RRM2 is related to resistance of breast cancer cells to chemotherapy and endocrine agents, as suppression of RRM2 led to increased chemo-sensitivity and reversed tamoxifen-resistant cell proliferation, reduced tumor growth and cell motility, as well as activated pro-apoptotic pathways (Chen et al. 2019). This evidence concerns the gene RRM2 and breast carcinoma.