The EP4 receptor is one of four GPCRs that mediate the actions of prostaglandin E2 (PGE2). The diverse effects of PGE2 acting via EP4 receptors point to the need to identify novel agonists and antagonists, both to further elucidate the function of this receptor subtype and for use as therapeutics for various diseases. Cayman's EP4 Receptor (rat) Activation Assay Kit (cAMP) consists of a 96-well plate coated with a transfection complex containing a DNA construct for rat EP4 Receptor (EP4 Reverse Transfection Strip Plate). Cells grown on the transfection complex will express EP4 at the cell surface. Binding of agonists to EP4 stimulates cAMP generation and increases intracellular cAMP levels, which can be measured by a competitive EIA using the Mouse Anti-Rabbit IgG Coated Plate and the reagents included in the kit. An EP4 agonist, PGE2, is included in the kit as a positive control.