BRCA1 and cancer: BRCA1 binds to EZH2, a component of the PRC2 in mouse and human mammary epithelial cells, acting as a competitive inhibitor of HOTAIR. Reduced BRCA1 expression, which is often observed in cancer allows HOTAIR to bind to PRC2, promoting reprogramming of breast epithelial cells to aggressive cancer cells (Wang et al., 2013).