Autocamtide-2-related inhibitory peptide is a highly specific and potent inhibitor of CaMKII with an IC₅₀ of 40 nM. IC50 & Target: IC50: 40 nM (CaMKII)^[1]. In Vitro: It is found that Autocamtide-2-related inhibitory peptide (a novel synthetic peptide ATP) is a potent inhibitor of CaM-kinase II with an IC₅₀ of 40 nM, which is active in the presence or absence of Ca²⁺/calmodulin. It is 50 and 500 times more potent than CaMK-(281-302Ala286) and KN-93,respectively, under the assay condition used^[1].