MTA2 and Alzheimer disease: The 6hTau mice were inoculated with AD-, PiD-, CBD-, and PSP-tau extracts, which induced the spread of tau seeds bearing strain-specific structural and seeding properties, such that AD-tau injection induced a mixed 3R and 4R tau pathology, PiD-tau selectively induced 3R tau pathology, and CBD- and PSP-tau injection selectively induced 4R tau pathologies—as determined by staining with 3R and 4R-specific antibodies.