Secreted tau is dephosphorylated compared to intracellular tau.

<p>(A, B, E, F, G, H, I and K) Secreted tau was phosphorylated at T181, S199, T212, S214, T217, S262, S409 and at the epitope of the AT180 antibody (T231/S235) but to a lesser extent than intracellular tau. (C, D, J and L) No signal was detected in M with the phospho-tau antibodies directed against phosphorylated S202 (CP13), T205 (pT205), S422 (pS422) and the S396/S404 (PHF-1) whereas a strong signal was observed in L with these antibodies. Tau12 antibody was used to reveal total tau in M and L. The pattern of each antibody was analyzed at least in 3 sets of experiments.