Tamoxifen is an orally active selective estrogen receptor modulator (SERM) that acts as an estrogen antagonist in breast cells and an agonist in bone, liver, and uterine cells. It can be used to induce gene knockout and liver injury models in mice, and also exhibits multiple biological activities, including activation of Hsp90, induction of autophagy and apoptosis, and inhibition of EBOV and MARV viral infections.