MAPT and Alzheimer disease: From this study, we identified 6 phosphorylation sites that are modified in pre-symptomatic normal individuals, 7 additional sites that are phosphorylated in a subset of individuals that are pre-symptomatic or definite AD, and 6 more sites that are phosphorylated in definite AD cases (total 19 sites, numbered according to 2N/4R tau: Additional file 1: Fig.S3a).