 These LPL receptor genes are also sometimes referred to as "Edg" (an acronym for endothelial differentiation gene).The ligands for LPL-R group are the lysophospholipid extracellular signaling molecules, lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P).The term "lysophospholipid" (LPL) refers to any phospholipid that is missing one of its two O-acyl chains.