Hence, thisstudy aimed to evaluate the possible role of miR-21 in the pathogenesis of ADvia phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/protein kinase B(AKT)/glycogen synthase kinase-3beta (GSK-3β) signaling.Materials and Methods:The miR-21 expression in the brain tissues of patients with AD, as well asnormal brain tissues and Aβ1-42-stimulated SH-SY5Y cell line (AD model) wasexamined by in situ hybridization and quantitative real-time polymerase chainreaction. The gene discussed is GSK3B; the disease is Alzheimer disease.