GPRC5B is a G protein-coupled receptor induced by retinoids. GPRC5B shows some homology to the metabotropic glutamate receptor-like family of GPCRs. In mice, GPRC5B has been shown to regulate neuronal differentiation in the developing neocortex. Additionally, GPRC5B is expressed in breast cancer cell lines versus absence in normal control cells, and may be an effective biomarker for breast cancer. In immunohistochemistry, GPRC5B has membranous and cytoplasmic positivity throughout the central nervous system, the kidney, reproductive tissues, the breast, gastrointestinal tract, kidney and a few other tissues. References: Front Pharmacol. 2018 May 22;9:431, PMID: 29872392; Development 2013 140: 4335-4346; doi: 10.1242/dev.099754