Agonist activity (arrestin recruitment) was determined in GPCR Tango assays, as outlined in the Methods. Normalized results (basal was set as 0% and reference Emax was set as 100%) represented mean ± SEM from minimum of n assays (n = 2 for A and B, n = 3 for C–E), each performed in triplicate, and were analyzed in Prism. Panels A–E represent a dose response curve for A1-adenosine (A), a2-adrenergic (B), 5-HT6 receptors (C), CB1 receptors (D), or CB2 receptors (E).