BRCA1 is a tumor suppressor gene known to be implicated in the development of a subset of breast and ovarian cancers. The tumor suppressor properties of BRCA1 are generally thought to be linked to the gene's critical roles in the network of DNA damage response. In a recent report, BRCA1-mediated epigenetic repression at the promoter region of miRNA-155 was identified as a novel mechanism by which BRCA1 carries out its tumor suppressor functions.