MAPT and Alzheimer disease: However, our data indicate that in both AD and controls, levels of N368-cleaved Tau are similar in the soluble fractions, which contain the vast majority of Tau (Additional file 1: Figure S4; Figure S5B, E; Figure S6B, E), and are increased only in the insoluble fractions, where uncleaved Tau levels are also elevated (Fig. 6a, d).