The assay aims to discover and optimize novel beta-arrestin-biased ligands for beta2-adrenergic receptors (beta2-ARs) using a validated luminescent cell-based assay called the Tango assay. Biased agonism is a concept in molecular pharmacology that proposes ligands can induce distinct signal transduction cascades through seven transmembrane receptors (7TMRs) or G protein-coupled receptors (GPCRs). Beta-arrestins have been shown to interact with agonist-occupied 7TMRs and mediate activation of several signaling pathways upon stimulation of 7TM receptors even in the absence of G protein activation. The antagonist ligand carvedilol has been demonstrated to selectively activate beta-arrestin-mediated signaling pathways in beta2-ARs. Is the molecule effective to this assay?