PSEN1 and Alzheimer disease: Because tau hyperphosphorylation is the pathological feature of AD, increased hyperphosphorylated tau protein have been reported in the brains of APP/PS1 transgenic mice (Aso et al., 2012; Busche and Hyman, 2020), we then used the AT8 (PHF-tau, Ser202/Thr205) antibody to detect the level of the phosphorylated tau in this model.