Estrogen rapid action via protein complex formation involving ERalpha and Src.

This review provides insight into biomolecular knowledge regarding the non-genomic actions of estrogen in hormone-dependent breast cancer, particularly its role in the rapid stimulation of pathways that transmit signals to increase cell division or decrease programmed cell death. Until recently, attention to estrogenic effects focused primarily on events in the nucleus, where most estrogen receptors (ERalpha and beta) reside. However, a fraction of ERalpha associated with the cell membrane also participates in rapid estrogen-induced cell membrane-mediated events via formation of a protein complex with many signaling molecules, leading to activation of the mitogen-activated protein kinase and Akt signaling pathways. Understanding the mechanisms underlying these relationships, with the aim of abrogating specific steps, should lead to more targeted strategies to treat hormone-dependent breast cancer.