EPOR and breast cancer: On the other hand, high levels of EPOR mRNA in myeloma were associated with a better prognosis (30); recurrence-free survival was significantly improved in ER +/EPOR + breast cancer patients with untreated tamoxifen in breast cancer (41), and in the breast cancer cell lines, RAMA 37 cells (low EPOR expression) had a stronger proliferation ability than RAMA 37-28 cells (high EPOR expression), suggesting that high EPOR expression can reduce the ability of cells to divide (42).