The level of phosphorylation of human tau at residues Ser 409, Ser 396 and Ser 202/Thr 205 was dependent on the age of the animals, progressively increasing between 1.5 months and 7 months post-injection (Fig. 5a). Remarkably, tau phosphorylation on residues Ser 396, Ser 202/Thr 205, Thr 181 and Thr 231 was more abundant on WT tau than on P301S tau (Fig. 5a). In 7 month-old mice, this effect was particularly evident on the phosphorylation of the Ser 396, Ser 202/Thr 205 and Thr 181 residues. Therefore, although P301S tau accumulates as a function of age, the relative contribution of phosphorylation on certain residues is more pronounced for WT tau. In contrast, age and mutation effects were different for other phosphorylation sites. The level of phosphorylation of Ser 409 and Thr 212 was nearly identical for WT and P301S tau (Fig. 5a). In particular, phosphorylation of Thr 212 showed no dependency on the presence of tau mutation and age.