PHF1 and Alzheimer disease: We did not find any significant alteration of tau phosphorylation at Ser199, Ser202/Thr205 (AT8), Thr212, Ser214, Thr217, Ser262, Ser396/404 (PHF‐1), and Ser422 in AD O‐tau‐injected hippocampi by Western blots (Figure 4).