In breast tumors with wild-type BRCA1, GPRC5A expression is higher than in BRCA1-mutated tumors. In vitro experiments show that knockdown of BRCA1 results in decreased expression of GPRC5A in MDA-MB-231 breast cancer cells, while the opposite results are obtained with BRCA1 overexpression [32]. This evidence concerns the gene BRCA1 and breast cancer.