Y₁R expression in MCF-7 cells is abrogated by antiestrogens in vitro.

<p> Effect of the pure ER antagonist fulvestrant on the estrogen stimulated Y₁R expression in MCF-7 (L) cells. A: Inhibition of estradiol (E2, 1 nM) induced Y₁R expression (determined with [³H]-UR-MK114, 12 nM) by the full ER antagonist fulvestrant. Incubation period: 48 h; basal expression: EMEM containing ct-FCS and vehicle. Mean values ± standard error of the mean (SEM); *p<0.001 compared to vehicle. B: Concentration-dependent inhibition of the estradiol (1 nM) induced Y₁R expression by fulvestrant. The IC₅₀ value ± SEM was calculated from two independent determinations performed in triplicate. The Y₁R up-regulation induced by 1 nM 17β-estradiol (E2) was set to 100%.