Immunoblots of SEPT11 confirm proteomic findings. (a) Frontal cortex samples from individual FTLD-U and control cases were sequentially extracted with buffers containing triton X-100, sarkosyl, and urea. Urea fractions were immunoblotted with an affinity purified SEPT11 rabbit polyclonal antibody raised to a peptide at the extreme N-terminus. (b) Preabsorption using the immunizing peptides quenches immunoreactivity with the exception of a faint non-specific band at ~40 kDa. (c) Overexposed immunoblot of urea fractions from additional FTLD-U and control cases detects SEPT11 at its expected Mr (49 kDa), as well as additional N-terminal species at ~45 kDa, ~37 kDa, and ~28 kDa. (D) Quantification in 7 FTLD-U cases and 9 controls of immunoblot band intensities for 49 kDa band (top panel) and all 3 SEPT11 lower Mr fragments (bottom panel). The band at ~40 kDa that did not preabsorb in (b) was excluded from the analysis.