Illustration of an estrogen receptor (ER), encoded by the ESR1 gene binding to a DNA strand (deoxyribonucleic acid, purple). ER are activated by estrogen molecules (faint orange) buried in the ligand binding domain. The ordered (pink) and disordered (yellow) regions of the ER are based on AlphaFold Artificial Intelligence prediction of estrogen receptor structure. Estrogen receptor is the target of selective estrogen receptor modulators (SERMs) used in breast cancer treatment, including tamoxifen, raloxifene, toremifene, lasofoxifene, clomifene, femarelle and ormeloxifene.