Prostaglandin E2 (PGE2) binds to four receptor subtypes: EP1, EP2, EP3, and EP4, which are all membrane-bound G protein-coupled receptors (GPCRs).{9114,6742,57668} The EP4 receptor was originally thought to be a subtype of the EP2 receptor but was later found to be a distinct receptor with sequence differences.{2035,3178} It is expressed in many tissues, including the intestine, heart, kidney, lungs, and brain, and is also expressed in peripheral blood leukocytes and macrophages.{57668} The EP4 receptor is coupled to G?s, and its activation increases intracellular cAMP levels leading to tissue-specific effects. It induces smooth muscle relaxation, angiogenesis, T cell expansion, osteoblast differentiation, and bone resorption and inhibits TNF-? production in monocytes and macrophages, among other activities. PTGER4, the gene encoding the EP4 receptor, is overexpressed in a variety of cancers, and antagonism of the receptor in animal models inhibits tumor growth and angiogenesis.{57669} In contrast, EP4 receptor activation has anti-inflammatory and neuroprotective activities in vitro and in animal models.{57670,57671} Cayman’s EP4 Receptor (C-Term) Polyclonal Antibody can be used for immunocytochemistry (ICC), immunohistochemistry (IHC), and Western blot (WB) applications.