Figure. Concentration-dependent activation of P2RY1 by ADP. Reporter cells were transfected with either the expression plasmid for purin­ergic receptor P2Y1 (P2RY1) or the mock plasmid and treated with various concentrations of adeno­sine di­phos­phate (ADP). Data points shown are the mean ± SEM of an experiment performed in triplicate, and the curve is a fit to Hill equation with an EC50 of 3.3 µM.