Scientists identify protein involved in restoring effectiveness of common treatment for breast cancer

Breast cancer is the most frequently diagnosed cancer among women, with estrogen-receptor-positive (ER+) being the most common type. Drugs used to treat this cancer, such as tamoxifen and Faslodex, block the hormone estrogen receptor that ER+ cancer cells need to grow. One problem with these treatments is that many tumors initially responsive to the drugs develop resistance, making the medicines less effective.