The link between a loss of acetylation on KXGS motifs and disease pathogenesis is further strengthened by the observation that KXGS motifs are ubiquitinated in pathological tau purified from post-mortem human brain tissue in AD [38] (Figure 1), thereby indicating such ubiquitination would preclude another post-translational modification, acetylation, from occurring. Here, MAPT is linked to Alzheimer disease.