In neurons transduced with AAV-tau, HT7 immunostaining was used to reveal the neuronal processes expressing human tau, and determine the frequency of filopodial protrusions in neurons expressing each of the different tau variants. A similar number of filopodia was observed in neurons overexpressing WT and P301S tau (Fig. 7a and b). Remarkably, the effect of vinblastine on the formation of filopodia was significantly diminished in neurons overexpressing 2P tau, compared to both WT and P301S tau. In neurons overexpressing 2P tau, the number of filopodia was not significantly different from the control neurons not exposed to vinblastine. This result indicates that this form of tau has enhanced protective effects against microtubule destabilization caused by vinblastine.