All are TRUE about protease activated receptors, EXCEPT:

Protease activated receptors (PARs), a family of four seven-transmembrane G protein-coupled receptors (PAR1, PAR2, PAR3, PAR4), act as targets for signalling by various proteolytic enzymes (thrombin, trypsin). PARs are characterized by a unique activation mechanism involving the proteolytic unmasking of a tethered ligand that stimulates the receptor. They release PGE2 and this inturn protects the epithelium. Ref: Ganong's Review of Medical Physiology, 21st Edition, Page 667