The metabolite S-Geranylgeranyl-L-glutathione (GGG) is a potent and selective ligand for P2RY8a Gα13-coupled receptor. GGG promotes internalization of P2RY8 and inhibits the migration of P2RY8-expressing cells (10 – 100 nM range in WEHI-231 cells). Extracellular GGG is shown to be actively transported by ABCC1 (ATP-binding cassette subfamily C member 1) and catabolized by GGT5 (gamma-glutamyltransferase-5) to S-geranylgeranyl-L-Cys-Gly plus glutathione.