MAPT and supranuclear palsy, progressive, 1: To further explore the seeding selectivity of the K12CFh substrate, we performed serial dilution analyses on several brain homogenates with confirmed 3R pathology (PiD), mixed 3R/4R pathology (sAD, fAD, CTE, PART), and controls that had either 4R pathology (PSP, CBD, AGD) or lacked tau pathology according to immunohistochemical analysis.