INS and Parkinson disease: Besides AD, Exendin-4 and a GLP-1R/GIPR dual agonist reversed PD-related and 6-OHDA-induced insulin pathway impairments, including lessened Akt activity, CREB induction and elevated Ser312-phosphorylated IRS-1 levels in vitro plus lowered Ser129 pIRS-1/IRS-1 ratios in vivo (Zhang L.Y. et al., 2021).