MAPT and Alzheimer disease: In accord with previous observations of tau in the human CNS in AD [8], our initial characterization of tau present in the soluble fraction of extracts from AD brain, antibodies generated against the very C-terminal end of tau (residues 422–440) did not reliably recognize seeding competent HMW tau from these preparations derived from AD brain frontal cortex, suggesting that the C-terminus may be cleaved or inaccessible.