PHF1 and supranuclear palsy, progressive, 1: Double immunofluorescence labelling demonstrated that not all HSP27-positive cells displayed PHF-1 immunoreactivity, but astrocytic tufts positive for PHF-1 and HSP27 were prominent in PSP brain sections and PHF-1-positive astrocytic plaques with HSP27 immunoreactivity in the center were typically seen in CBD brain sections.