Lysophosphatidic acid (LPA) a bioactive lipid produced by several cell types including postmitotic neurons and activated platelets is thought to be involved in various biological processes including brain development Three cognate G-protein coupled receptors encoded by lpa(1)/lp(A1)/Edg-2/Gpcr26 lpa(2)/lp(A2)/Edg-4 and lpa(3)/lp(A3)/Edg-7 mediate the cellular effects of LPA However many LPA-induced responses including phospholipase C activation Ca sup 2 /sup mobilization adenylyl cyclase activation proliferation JNK activation AKT activation and stress fiber formation were absent or severely reduced in embryonic fibroblasts derived from lpa(1)(-/-) lpa(2)(-/-) mice The lysophosphatidic acid receptor LPA2 or endothelial differentiation G-protein coupled receptor 4(EDG-4) is expressed most abundantly in testes and peripheral blood leukocytes It is reported to be a distinctive functional marker for ovarian carcinoma