(Arg)9 is a cationic cell-penetrating peptide.1,2 It has been used to deliver various cargo to cells, including fluorescent proteins and plasmids. (Arg)9 (5 and 10 µM) also protects primary rat cortical neurons from glutamate-induced excitotoxicity.3
1.Chang, M., Chou, J.-C., and Lee, H.-J.Cellular internalization of fluorescent proteins via arginine-rich intracellular delivery peptide in plant cellsPlant Cell Physiol.46(3)482-488(2005) 2.Lee, C.-Y., Li, J.-F., Liou, J.-S., et al.A gene delivery system for human cells mediated by both a cell-penetrating peptide and a piggyBac transposaseBiomaterials32(26)6264-6276(2011) 3.Meloni, B.P., Brookes, L.M., Clark, V.W., et al.Poly-arginine and arginine-rich peptides are neuroprotective in stroke modelsJ. Cereb. Blood Flow Metab.35(6)993-1004(2015)