A selective, ATP-competitive inhibitor of the serine/threonine kinase, glycogen synthase kinase 3β (Ki = 38 nM; IC50 = 104 nM); demonstrates neuroprotective effects by inhibiting tau phosphorylation (IC50 = 2.7 μM) at a GSK3-specific site (Ser396) in cells stably expressing human four-repeat tau protein and also by protecting β-amyloid-exposed N2A neuroblastoma cells against cell death.