2-Arachidonyl glycerol (2-AG) exhibits CB agonist activity at the CB1 receptor,{5306} is an important endogenous monoglyceride species,{6819} and is thus considered to be the natural ligand for the CB1 receptor. 2-AG can also be metabolized by COX-2 to form PG 2-glyceryl esters.{11045} In activated RAW 264.7 cells, PGD2 2-glyceryl ester is the primary product of 2-AG metabolism in the COX pathway.{11045} PGD2-SA is a stable analog of PGD2 2-glyceryl ester. Unlike PGD2 2-glyceryl ester and other fatty acyl 2-glyceryl esters, PGD2-SA will not isomerize to the less active primary (1-glyceryl) ester. The biological activity of PGD2-SA has not yet been determined.