PHF1 and Alzheimer disease: This is further supported by immunohistochemistry in brain tissues from AD and non-AD tauopathies, which consistently show the high immunoreactivity of tau inclusions to antibodies such as AT8 (p-tau202/205) or PHF1 (p-tau396/404), ultimately demonstrating that highly phosphorylated tau is a major pathological component of both AD and non-AD tauopathies [12].