AIM: To identify the differentially expressed proteinsbetween the human immortalized esophageal epithelial cellline (SHEE) and the malignant transformed esophagealcarcinoma cell line (SHEEC), and to explore new ways forstudying esophageal carcinoma associated genes.METHODS: SHEE and SHEEC cell lines were used toseparate differentially expressed proteins by two-dimensionalelectrophoresis. The silver-stained 2-D gels was scannedwith EDAS290 digital camera system and analyzed with thePDQuest 6.2 Software. Six spots in which the differentiallyexpressed protein was more obvious were selected andanalyzed with matrix-assisted laser desorption/ionization timeof flying mass spectrometry (MALDI-TOF-MS).RESULTS: There were 107±4.58 and 115±9.91 proteinspots observed in SHEE and SHEEC respectively, and themajority of these spots between the two cell lines matchedeach other (r=0.772), only a few were expresseddifferentially. After analyzed by MALDI-TOF-MS and databasesearch for the six differentially expressed proteins, One newprotein as well as other five sequence-known proteinsincluding RNPEP-like protein, human rRNA gene upstreamsequence binding transcription factor, uracil DNA glycosylase,Annexin A2 and p300/CBP-associated factor werepreliminarily identified.CONCLUSION: These differentially expressed proteinsmight play an importance role during malignanttransformation of SHEEC from SHEE. The identification ofthese proteins may serve as a new way for studyingesophageal carcinoma associated genes.Xiong XD, Xu LY, Shen ZY, Cai WJ, Luo JM, Han YL, Li EM.Identification of differentially expressed proteins between humanesophageal immortalized and carcinomatous cell lines by twodimensionalelectrophoresis and MALDI-TOF-massspectrometry.