GSK3B and Alzheimer disease: Exendin-4 treatment reversed the intracerebroventricular-streptozotocin (ICV-STZ) -induced decline in the levels of phosphorylation of Akt at Ser473 and glycogen synthase kinase 3β (GSK-3β) at Ser9, a key kinase in AD, leading to decrease hyperphosphorylation of tau in rat hippocampus (182).