PHF1 and Alzheimer disease: Treatment of 3xTg-AD slices for 48 h treatment with 40 or 60 μM BTA-EG4 did not affect the amount of total tau, tau dephosphorylated at Ser199/202/Thr205 (Tau-1), or tau phosphorylated at Ser396/404 (PHF-1), relative to controls (Fig. 3a,b).