PHF1 and Alzheimer disease: Since CCI acutely affects tau phosphorylation in 3xTg-AD mice at several sites, specifically at Serine 199, Serine 396 and Serine 404, as detected with phospho-specific tau antibodies pS199 and PHF1, respectively [15], we tested whether CCI increased tau phosphorylation in injured TauP301L mice by staining with these antibodies.