PKA-induced phosphorylation of ER alpha at serine 305 and high PAK1 levels is associated with sensitivity to tamoxifen in ER-positive breast cancer
Phosphorylation of estrogen receptor alpha at serine 305 (ER alpha S305-P) by protein kinase A (PKA) or p21-activated kinase 1 (PAK1) has experimentally been associated with tamoxifen sensitivity. Here, we investigated the clinical application of this knowledge to predict tamoxifen resistance in ER-positive breast cancer patients. Using immunohistochemistry, a score including PAK1 and co-expressio