Selective hormone-dependent repression of estrogen receptor beta by a p38-activated ErbB2/ErbB3 pathway.

Deregulated signaling of ErbB2 receptor tyrosine kinase is often associated with hormone resistance in estrogen receptor alpha (ERalpha)-positive breast cancers, establishing a relationship between ErbB2 and ERalpha pathways. Although ERalpha and ERbeta are expressed in many breast cancer cells, the response of ERbeta to ErbB2 signaling is less well defined. In the present study, we demonstrate that ERbeta activity can be modulated by ErbB2 signaling in ER-expressing breast cancer cells.