MLNR (GPR38, Motilin Receptor) is a G protein-coupled receptor that mediates smooth muscle contraction and controls gastrointestinal motility by binding motilin. The antibiotic erythromycin-A also induces smooth muscle contraction when binding to the motilin receptor. Associations exist between the motilin peptide and several gastrointestinal diseases, such as Crohn's disease, inflammatory bowel disease, and ulcerative colitis. The motilin receptor may also be implicated in the progression of these diseases. It is a target of numerous agonists in development for the potential acceleration of gastric emptying or for other therapeutic purposes. In immunohistochemistry, MLNR has membranous positivity in the gastrointestinal tract, brain, thyroid and bone marrow. References: Br J Pharmacol. 2013 Dec; 170(7): 1323–1332, PMID: 23189978