Cell-permeable. KN-62 is a selective inhibitor of Ca²⁺/calmodulin-dependent kinase type II (CaMKII; IC₅₀= 900 nM). It binds directly to the calmodulin binding site of the enzyme. It does not affect the activity of several other kinases when tested at 10 µM. KN-62 also acts as a non-competitive antagonist of the purinergic receptor P2RX7 (IC₅₀ = 15 nM).