MAPT and Alzheimer disease: DA9 antibody could recognize both phosphorylated and non-phosphorylated tau forms [32], and in AD samples 85.6 ± 5.1% of bipartite synapses were tau (DA9)-positive, with a distribution ratio of 34.6%:47.1%:3.8% (pre-only/post-only/both) (Figure 4B).