SSTR4 is a receptor for somatostatin-14. The activity of this receptor is mediated by G proteins which inhibits adenylyl cyclase. It is functionally coupled not only to inhibition of adenylate cyclase, but also to activation of both arachidonate release and mitogen-activated protein (MAP) kinase cascade. It mediates the antiproliferative action of somatostatin in tumor cells. SSTR4 is also involved in the regulation of inflammatory response and pain control, and agonists to SSTR4 are of interest as potential inflammation and pain therapies. In immunohistochemistry, SSTR4 has membranous positivity in the central nervous system, prostate and pancreas. In the brain, SSTR4 stains populations of neurons in the hippocampus, amygdala, cortex, cuneate, and medulla, with lower levels of positivity in other areas of the nervous system. It is also positive in a wide range of malignancies. References: ACS Med Chem Lett. 2015 Feb 12; 6(2): 110–111, PMID: 25699156