MAPT and Alzheimer disease: We next examined the distribution of the P-Ser396 pTau (PS396), a preferred site of GSK-3 β phosphorylation activated by phospho-AKT1 (S473) [81], in combination with the S202 and S205 phosphorylated forms of tau labelled by AT8, 4G8 and Iba1 staining in IHC multiplex chromogenic experiments (n = 4 AD).