GPR56 (ADGRG1) is a member of the adhesion G-protein coupled receptor (GPCR) family, responsible for the regulation of cell adhesion, migration, polarity, and guidance. GPR56 levels are increased in many cancer types and seems to be relevant for tumor cell migration and invasion^1,2. GPR56 structure is characterized by a long extracellular domain that is involved in cell-to-cell and cell-to-extracellular matrix interactions. The receptor contains a GPS motif, responsible for cleaving the protein. Seven different glycosylation sites along its N-terminal fragment are present^1-3.

Expression of Gpr56 mRNA can be found in neuronal progenitor cells of the cerebral cortical ventricular and subventricular zones during periods of neurogenesis. Studies show that GPR56 protein knockdown promotes mesenchymal differentiation of glioma stem-like initiating cells, accompanied by increased radioresistance in vitro and in vivo^1-3.

Mutations in GPR56 may cause bilateral frontoparietal polymicrogyria, a cobblestone-like cortical malformation, characterized by overmigrating neurons and the formation of neuronal ectopias on the surface of the brain^2,3.