TDP-43 phosphorylation occurs in the CA1 region of the hippocampus of 208 TDP-43 Tg mice. (A and B) IHC for p409/410 TDP-43 is positive predominantly in the CA1 subfield of the hippocampus, with little to none in other regions where 208 CTF TDP-43 is expressed, including (C) the cortex, and (D) the CA3 and (E) DG of the hippocampus. IHC for p403/404 TDP-43 showed no immunoreactivity in (F) littermate controls but was positive in (G–I) 208 TDP-43 Tg mice at all time points examined, including 2 weeks, 6 and 19 months. Scale bars: A, 500 μm; B–I, 50 μm.