Tau phosphorylation and neuronal apoptosis induced by the blockade of PP2A preferentially involve GSK3β

► Tau phosphorylation and neuronal apoptosis were induced by OKA, an inhibitor of PP2A. ► Lithium and 6-BIO prevented OKA-induced tau phosphorylation and neuronal apoptosis. ► Silencing of GSK3β by hairpin siRNA reversed tau phosphorylation and neuronal apoptosis. ► Inhibition of DYRK1A and CDK5 failed to prevent OKA-induced neuronal apoptosis. ► 6-BIBEO, a new GSK3β inhibitor reversed OKA-induced tau phosphorylation and apoptosis.