MAPT and Alzheimer disease: The organization of neuronal PCH was then analysed in neurons from either Braak 6 AD or control brains by immunofluorescence and confocal microscopy using Hoechst staining of DNA, anti-H3K9me3 antibodies and the phospho-dependent AT8 antibody that recognizes Tau phosphorylated at Ser202/Thr205, an AD-relevant Tau epitope present from the early to late stages of Tau pathology.