Production of lysophosphatidic acid (LPA) via two main pathways: Half of serum LPA is formed through the generation of lysophospholipids (LPLs), such as lyso-PC (LPC), lyso-PE (LPE), and LPS, by secreted PLA2 (sPLA2-IIA) or PS-PLA1 from membrane phospholipids of activated platelets, followed by conversion of the LPLs to LPA by autotaxin (ATX). The other half of serum LPA can be generated by sequential action of lecithin: cholesterol acyltransferase (LCAT) or PLA1 and ATX. LPA produced by ATX has various roles mediated by LPA receptors. LPA in cells may originate from PA. In this pathway, a PLD or DAG kinase convert lipids in PA and then PA is hydrolyzed by PLA1 or PLA2.