STO-609 is a cell-permeable inhibitor of calcium/calmodulin-dependent kinase kinases (CaMKK) isoforms CaMKKα and CaMKKβ (Ki = 80 and 15 ng/ml, respectively). It also blocks autophosphorylation of both isoforms. STO-609 less potently inhibits CaMKII (IC50 = 10 μg/ml) and is minimally effective against several related kinases. It is bound, in CaMKKβ, in the ATP-binding pocket found in the kinase domain. STO-609 is used to evaluate the action of CaMKK isoforms both in vitro and in cells.
