The Ready-to-Assay EP4 Prostanoid Receptor Frozen Cells are a simple, thaw-and-assay cell format for use in studying drug candidates (small molecules or biologics) targeting GPCRs. This assay assesses ligand (e.g. prostaglandin E2) based activation of PTGER4 GPCR activity via detection of increasing levels of intracellular calcium. The included cell line overexpresses PTGER4 alongside exogenous high levels of a promiscuous G-protein, coupling the receptor to the calcium signaling pathway. ChemiBrite cells also express a clytin variant, allowing for luminescent as well as fluorescent signal detection. Upon activation of PTGER4, the resulting calcium activity can be assayed in either detection mode. Ready-to-assay kits consist of two vials of the stably modified clonal cell line in a convenient thaw-and-use format. For detailed product information, User manual and datasheet, visit www.discoverx.com/products-applications/frozen-cells.