Potent and selective casein kinase 1ε (CK1ε) and CK1δ inhibitor (IC50 values are 7.7 and 14 nM respectively) that displays > 30-fold selectivity over 42 other common kinases. Inhibits PER protein nuclear translocation (EC50 = 290 nM) causing phase shifts in circadian rhythms and attenuates methamphetamine-stimulated locomotion in vivo.