MAPT and tauopathy: To determine whether FAF2 activity towards tau aggregation was effective in a mammalian model of tauopathy, we used AAV9 to deliver transgenes to wild-type (WT) or tau transgenic mice that harbor one copy of a transgene expressing 1N4R human tau with a P301S mutation driven by the mouse prion promotor (PS19).35 We generated AAV9 encoding GFP as a negative control as well as GFP-tagged FAF2 and FAF2PS which we delivered at postnatal day 1 (P1) by intracerebroventricular (ICV) injection (Figure 5C).