Sensitivity of MCF-7 and MDA-MB-231 (with stable transfection of vector, wild type ERα, or mutant ERα) cell lines to AFP464 in the absence or presence of 17β-estradiol (E2) or endoxifen^a.

aCells were cultured in normal medium with 10% FBS or in medium with charcoal-striped FBS and were treated with AFP464 for 120 h in the absence or presence of 17β-estradiol (E2) (10 nM) or endoxifen (50 nM). Data are expressed as the mean ± standard deviation of the IC50 values determined from three independent experiments. *Statistically significantly different from that in the absence of endoxifen, t-test, P<0.05. ND, not determined.