text: The involvement of EP1 and EP2 receptors is indicated by studies with the EP1 selective agonist 17-phenyl trinor PGE2, and the << EP2 >> selective agonist butaprost (which stimulate), as well as by studies with the antagonists SC-51089 (EP1 specific) and [[ AH 6809 ]] (EP1 and EP2 specific).