Since our results showed that phosphorylation of ER-α Ser167, but not ER-α Ser118, was predictive of response to endocrine therapy, they suggest that, in breast cancer, phosphorylation of ER-α Ser118 occurs frequently without estradiol, whereas phosphorylation of ER-α Ser167 may occur frequently in response to estradiol binding. The gene discussed is ERAL1; the disease is breast cancer.