BRCA1 (breast and ovarian cancer susceptibility protein 1) is a nuclear phosphoprotein that plays a role in maintaining genomic stability and acts as a tumor suppressor in combination with other tumor suppressors, DNA damage sensors, and signal transducers to form a large multi-subunit protein complex known as BASC (for BRCA1 associated genome surveillance complex). BRCA1 associates with RNA polymerase II, and through the C terminal domain, also interacts with histone deacetylase complex. The BRCA1 protein thus plays a role in transcription, DNA repair of double-stranded breaks, and recombination. Many alternatively spliced transcript variants, some of which are disease-associated mutations, have been described for the BRCA1 gene, but the full-length natures of only some of these variants has been described. Mutations in the BRCA1 gene are responsible for approximately 40% of inherited breast cancers and more than 80% of inherited breast and ovarian cancers. Anti-BRCA1 is used for rapid screening of these type of cancers.