Additionally, studies have shown that the expression levels of ERK2 (MAPK1) in the hippocampus of AD patients remain unchanged, but phosphorylated ERK2 is increased (Ferrer et al., 2001b; Khezri et al., 2023), which is associated with Tau protein phosphorylation (Kerr et al., 2006). The gene discussed is MAPK1; the disease is Alzheimer disease.