GRKs-IN-1 hydrochloride, Compound 14as, has remarkable potency against and selectivity for G protein-coupled receptor kinase 2 GRK2 (IC50=130 nM) and GRK5 (IC50=7.1 μM).GRKs-IN-1 hydrochloride is a derivative 14as of paroxetine, shows a 100-fold improvement in cardiomyocyte contractility assays over paroxetine[1]. [1]. Waldschmidt HV, et al. Structure-Based Design of Highly Selective and Potent G Protein-Coupled Receptor Kinase 2Inhibitors Based on Paroxetine. J Med Chem. 2017 Apr 13;60(7):3052-3069.