Identification of the 11.1 kDa protein. (A) 2-DE maps of whole cell lysates from HT29 (left panel) and COLO-320 (right panel), which showed high and low expression of the 11.1 kDa protein, respectively. The 4 spots indicated by the arrows were selected on the basis of the experimental molecular mass (m/z 11,072) and experimental pI (7.0-7.5) of the candidate protein. (B) The MS/MS spectrum of tryptic-digested m/z 550.29 recorded from spot 4. The amino acid sequence of this peptide fragment is highlighted on the spectrum.