Exendin-4 (Ex-4), another GLP-1RA that is homologous to commercially available exenatide, ameliorated IR in primary neurons through insulin receptor substrate-1 (IRS-1), AKT, and glycogen synthase kinase-3β (GSK-3β) pathways; GSK-3β significantly contributes to neuroprotection given its role in tau hyperphosphorylation in AD pathology [46]. This evidence concerns the gene AKT1 and Alzheimer disease.