MRS-1191 is a potent and selective A3 adenosine receptor antagonist with a KB value of 92 nM, a Ki value of 31.4 nM for human A3 receptor and an IC50 of 120 nM for CHO cells[1]. MRS-1191 is a click chemistry reagent, it contains an Alkyne group and can undergo copper-catalyzed azide-alkyne cycloaddition (CuAAc) with molecules containing Azide groups.