ESR1 and breast carcinoma: Our data revealed that higher RES concentrations (up to 100 μM) significantly inhibited proliferation in both ERα- and ERα+ breast cancer cell lines, with IC50 values of 15.1 ± 4.9 μM for MDA-MB-231 cells and 37.4 ± 14.5 μM for MCF-7 cells.