Description_x000D_ Biochem/physiol Actions_x000D_ AZ3451 is a potent and selective allosteric antagonist of protease-activated receptor 2 (PAR2), a G protein-coupled receptor thought to be involved in inflammatory diseases, pain, allergic associated diseases (eosinophil migration, mast cells) and cancers. AZ3451 was found to bind to a remote allosteric site outside the helical bundle that is different from the site previously found on PAR1, and had an IC50 value of 23 nM. AZ3451 was able to completely inhibit ERK phosphorylation when added to 1321N1 cells overexpressing wild-type human PAR2.