Objective:The aim of this study was to establish reproducible two-dimensional electrophoretic assay used for profiling and identification of differentially expressed proteins in human stage Ⅰ lung adenocarcinoma and paired normal tumor-adjacent tissue.Methods:The proteins from 12 human stage Ⅰ lung adenocarcinoma tissues and normal tumor-adjacent tissues were separated using isoelectric focusing electrophoresis(the first dimension) and the subsequent homogeneous SDS-polyacrylamide gel electrophoresis(SDS-PAGE)(the second dimension).The differentially expressed proteins were determined with PDQuest image analysis software,and identified using matrix-assisted laser desorption/ionization time of flight mass spectrometry(MALDI-TOF-MS) and database searching.Results:The well-reproducible 2-DE gel patterns of human stage Ⅰ lung adenocarcinoma and normal tumor-adjacent tissues were profiled and 26 differentially expressed proteins uncovered.Nine of these 26 protein spots were cut out from the preparation gels and determined with MALDI-TOF-MS.Searching against the protein database,four candidate proteins were identified.They were 60S acidic ribosomal protein P2,Cathepsin B1,Apolipoprotein A-I precursor,and La 4.1 protein.Conclusion:In this study,high reproducible 2-DE gel protein images of human stage Ⅰ lung adenocarcinoma and paired normal tumor-adjacent tissues were achieved successfully,and 4 differentially expressed proteins were revealed.These data will be helpful for screen of early biomarker and study of molecular mechanisms of human lung adenocarcinoma. Objective: The aim of this study was to establish reproducible two-dimensional electrophoretic assay used for profiling and identification of differentially expressed proteins in human stage I lung adenocarcinoma and paired normal tumor-adjacent tissue. Methods: The proteins from 12 human stage I lung adenocarcinoma tissues and normal tumor-related tissues were separated using isoelectric focusing electrophoresis (the first dimension) and the subsequent homogeneous SDS-polyacrylamide gel electrophoresis (SDS-PAGE) (the second dimension). The differentially expressed proteins were determined with PDQuest image analysis software, and identified using matrix-assisted laser desorption / ionization time of flight mass spectrometry (MALDI-TOF-MS) and database searching. Results: The well-reproducible 2-DE gel patterns of human stage I lung adenocarcinoma and normal tumor-adjacent tissues were profiled and 26 differentially expressed proteins uncovered. Neine of these 26 protein spots were cut out fr om the preparation gels and determined with MALDI-TOF-MS. Search against the protein database, four candidate proteins were identified. They were 60S acidic ribosomal protein P2, Cathepsin B1, Apolipoprotein AI precursor, and La 4.1 protein. Confluence: In this study , high reproducible 2-DE gel protein images of human stage I lung adenocarcinoma and paired normal tumor-adjacent tissues were completely successfully, and 4 differentially expressed proteins were revealed. the data will be helpful for screen of early biomarker and study of molecular mechanisms of human lung adenocarcinoma.