STO-609 is a naphthoyl fused benzimidazole cell-permeable compound. It is known to be a very potent and selective ATP-competitive CaMKK inhibitor. STO-609 has been shown to bind to the CaMKK catalytic domain, thus inhibiting autophosphorylation. STO-609 has not been found to significantly affect the activities of MLCK, CaMKII, CaMKI, CaMKIV, PKC, PKA, or p42 MAP kinase. It has been observed to inhibit AMP-activated protein kinase phosphorylation. STO-609 is an inhibitor of CaMKK α and CaMKK β and an activator of aryl hydrocarbon receptor.