CTSB as the representative of protein identification using ESI-Q- TOF-MS/MS. (A &B) Mass spectrogram of tryptic peptides from spot #15. (C) Protein sequence of CTSB. The matched peptides are underlined. (D) Western blotting confirmation of the proteins CTSB, corresponding to the spot #15. As shown, expression of CTSB was up-regulated in lung SCC compared with adjacent normal tissues. The experiment was repeated three times. (E) The level of CTSB was 2.52 ± 0.31 in the lung SCC group, and 0.42 ± 0.07 in control (adjacent normal tissues) (P < 0.05). β-actin was used to normalize for any differences in protein loading between lanes.