BRCA1(redirected from breast cancer type 1 susceptibility protein)
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symbol for a breast cancer gene. BRCA1 is a tumor suppressor gene. A healthy BRCA1 gene produces a protein that protects against unwanted cell growth. The protein is packaged by the cell's Golgi apparatus into secretory vesicles, which release their contents on the cell's surface. The protein circulates in the intracellular space, attaching itself to neighboring cell receptors. The receptors signal the cell nuclei to stop growing. When the gene is defective, it produces a faulty protein that is unable to prevent proliferation of abnormal cells as they evolve into potentially deadly breast cancer. BRCA1 may also normally inhibit ovarian cancer.