In summary, our data provide support for decursin and DA as potential novel breast cancer chemopreventive agents by targeting ERα signaling through inhibiting its transcription, stability and abundance as well as nuclear translocation in estrogen-dependent MCF-7 cells, and by inducing ERβ in estrogen-independent MDA-MB231 cells, leading to cell-cycle arrest and proapoptotic actions. This evidence concerns the gene ESR1 and breast carcinoma.