The relevance of phosphorylated forms of estrogen receptor in human breast cancer in vivo

Estrogen receptor (ER)alpha activity is regulated by phosphorylation at several sites. Recently several antibodies specific for individual phosphorylated sites within ER alpha have became available. Validation and use of these antibodies suggests that several forms of phosphorylated ER alpha can be detected in multiple ER+ human breast tumor samples, thus providing relevance for investigating the regulation and function of phosphorylated ER alpha in human breast cancer. Generally, the phosphorylated ER alpha isoforms are associated with parameters that suggest that they are markers of an intact estrogen dependent signaling pathway and better clinical outcome with respect to tamoxifen therapy. Profiling of phosphorylated ER alpha may provide better biomarkers of endocrine therapy response over and above those currently available. (C) 2009 Elsevier Ltd. All rights reserved.