Gastric cancer (GC) is the fourth most common cancer worldwide and the second most common cause of cancer death.In thisstudy,to identify potential molecular markers and key tumorigenesis factors of GC,we performed a comprehensive proteomicanalysis of four gastric cell lines including one normal gastric cell line and three GC cell lines by label free LC-MS.All samples wereanalyzed in triplicates by LTQ-Obitrap.Two GC cell lines were further analyzed twice by Synapt G1.We unambiguously identified2,844 proteins based on more than 450 thousand tandem mass spectra at a false discovery rate of 0.1 ％at the spectrum level.