Lysophosphatidic acid (LPA) is a lysophospholipid produced by activated platelets that inhibits adenylate cyclase and stimulates DNA synthesis, changes in cell morphology, and increases in intracellular calcium in a variety of cultured mammalian cells. A growing family of GPCRs mediates the biological effects of LPA. The first LPA receptors described, LPA1-3, share relatively high sequence similarity and are related to the sphingosine 1-phosphate receptors S1P1-5 (Contos et al., 2000). Two more recently characterized LPA receptors, LPA4 and LPA5, are related to each other but are more distantly related to LPA1-3. LPA5, originally known as GPR92, mediates LPA-induced cytoskeletal changes, intracellular calcium flux and increased cAMP by coupling to G12/13, Gq, and Gs. (Lee et al., 2006). In addition to binding LPA, LPA5 is also activated by several other lipid-derived molecules, the most potent of which is farnesyl pyrophosphate (Oh et al., 2008). GPR92 is expressed in several tissues, most prominently in the CD8+ intraepithelial lymphocytes of the gastrointestinal tract (Kotarsky et al., 2006). Cloned human LPA5-expressing cell line is made in the Chem-1 host, which supports high levels of recombinant LPA5 expression on the cell surface and contains high levels of the promiscuous G protein Gα15 to couple the receptor to the calcium signaling pathway. Thus, the cell line is an ideal tool for screening for agonists, antagonists and modulators at LPA5.