3142887 VPAC2-R vasoactive intestinal polypeptide/pituitary adenylate cyclase-activating polypeptide mutual receptor, subtype 2 1 3142886 VPAC2-R VIP potently agonizes VPAC2 receptor 1 3142885 VPAC2-R VIP/PACAP-2 receptor 1 3142888 VPAC2-R VPAC2 receptor 1