IS: induced sputum. EBC: exhaled breath condensate. BALF: bronchoalveolar lavage fluid. 2D-PAGE: two-dimensional polyacrylamide gel electrophoresis. FT-ICR MS: Fourier transform-ion cyclotron resonance. GeLC-MS/MS: proteins are separated by standard SDS-PAGE gel which is then cut into 25 pieces. Each gel slice is then cleaved by trypsin and then further fractionated by LC separation. Peptide fragments are then analysed by MS/MS. 2D-DIGE: two-dimensional difference gel electrophoresis. MSBs: mesoporous silica beads. RP-LC: reverse-phase liquid chromatography.