MAPT and tauopathy: Our observations derived from combined [F-18]-MK-6240 sensitive autoradiography and immunohistochemistry, using this compound at similar concentrations used in vivo for PET studies, indicate that MK-6240 has high binding affinity for tau aggregates in AD brain tissue, but does not seem to bind to a significant extent to neuronal and glial tau aggregates in non-AD tauopathies such as PiD, PSP, CBD or CTE, or to Aβ, α-synuclein or TDP-43-containing lesions.