- Role of G protein-coupled receptor kinase 4 and beta-arrestin 1 in agonist-stimulated metabotropic glutamate receptor 1 internalization and activation of mitogen-activated protein kinases. Iacovelli, L., Salvatore, L., Capobianco, L., Picascia, A., Barletta, E., Storto, M., Mariggiò, S., Sallese, M., Porcellini, A., Nicoletti, F., De Blasi, A. J. Biol. Chem. (2003)