XPNPEP2 and Alzheimer disease: It has been shown that different cellular signaling pathways, such as protein phosphatase 2 A (PP2 A), glycogen synthase kinase 3 β (GSK3β), and phosphatase and tensin homologue (PTEN) are involved in AD neuropathology (Kumar and Bansal 2022; Sequeira and Godad 2024).