Immunohistochemical co-localization of active p70 S6 kinase (T389) with PHF-tau (labeled by AT8). Active p70 S6 kinase (red) was partially or fully co-localized with AT8-labeled PHF-tau (green) in neuronal cytoplasm (A1, A2, and A3), and in a few dystrophic neurites (B1, B2, and B3). Bar, 20 μm.