An endogenous glycerophospholipid signaling molecule and ligand for the LPA (EDG, endothelial cell differentiation gene family) receptors LPA1, LPA2 and LPA3. Potent mitogen, associated with endothelial cell, vascular smooth muscle cell, and fibroblast growth stimulation. Inhibits autophagy through inhibition of class III PI3 kinases associated with autophagosome formation.