MAPT and supranuclear palsy, progressive, 1: We found that there was a 3.4-fold increase in GFAP burden in slices cultured with Tau +ve PSP extract compared to medium alone and a 4.3-fold increase compared to Tau −ve PSP extract treatment (Fig. 7e), implying the astrogliosis observed is a result of the tau in PSP brain rather than any other factor.