Thus far, there has been no report of a selective P2Y4R agonists or antagonists. Nonselective P2Y agonists UTPγS,275 5-bromo-UTP,276 INS365, INS37217, and INS45973 also exhibit agonist activity for the P2Y4R.277,278 Recently, an anthraquinone derivative was synthesized and showed selective and noncompetitive antagonist activity at the hP2Y4Rs (IC50 = 233 nM).279 To the best of our knowledge, there has been no report of any PET radioligand for mapping of the P2Y4Rs thus far.
