LPA is a potent lipid mediator that elicits its effect through four distinct receptors - LPA1/EDG-2, LPA2/EDG-4, LPA3/EDG-7 and LPA4/GPR23.{11049,13009} OMPT is a selective agonist of the LPA3 receptor. It exhibits EC50 values of 68 nM and >6.8 µM for calcium mobilization in LPA3 and LPA2-expressing Sf9 cells, respectively.{11057} The (2S)-OMPT enantiomer is 5- to 20-fold more active than (2R)-OMPT in calcium release assays in both LPA3-transfected Sf9 and rat hepatoma Rh7777 cells.{13369}