MDA-MB-231 BC cells transfected with Y537S-ERα vectors and treated with compound 19 at increasing doses (from 1 nM to 100 μM) displayed a dose-dependent decrease of Y537S-ERα transactivation, with the highest inhibition registered at 100 μM concentration (65 ± 10 % inhibition as compared to vehicle) (Supplementary Figure 4). Here, ESR1 is linked to breast cancer.