Figure 2

Corepressors and tamoxifen-resistant breastcancers. Estrogen receptors (ER) can interact with either coactivators or corepressors. Tamoxifen, a common treatment for ERα-positive breast cancers, induces an ERα conformational change that favors recruitment of corepressors to repress proliferative genes controlled by ERα. However, some breast cancers show ERα recruitment of coactivators even in the presence of tamoxifen, thus resulting in activation of proliferative genes. Many of these tamoxifen-resistant breast cancers overexpress the oncogene ErbB2, which has been shown to increase coactivator levels and decrease corepressor levels, thus altering the delicate ratio between these critical factors.