ChEBI: Tamoxifen is a tertiary amino compound and a stilbenoid. It has a role as an estrogen receptor antagonist, a bone density conservation agent, an estrogen receptor modulator, an estrogen antagonist, an angiogenesis inhibitor, an EC 2.7.11.13 (protein kinase C) inhibitor, an EC 1.2.3.1 (aldehyde oxidase) inhibitor and an antineoplastic agent. It derives from a hydride of a stilbene.NCI Thesaurus (NCIt): Tamoxifen is an antineoplastic nonsteroidal selective estrogen receptor modulator (SERM). Tamoxifen competitively inhibits the binding of estradiol to estrogen receptors, thereby preventing the receptor from binding to the estrogen-response element on DNA. The result is a reduction in DNA synthesis and cellular response to estrogen. In addition, tamoxifen up-regulates the production of transforming growth factor B (TGFb), a factor that inhibits tumor cell growth, and down-regulates insulin-like growth factor 1 (IGF-1), a factor that stimulates breast cancer cell growth.