Abstract: Objective To explore the differentially expressed genes of gastric cancer, matched normal gastric tissue and premalignant lesions. Methods The differentially expressed cDNA bands were isolated and identified by fluorescent differential display and then reamplified by PCR.After being cloned, all cDNA fragments were sequenced. Through BLAST software, the sequencing results were compared with GenBank database for homology analysis. The expression of the cDNA fragment in different tissues was confirmed by Northern blot. SMART RACE（Rapid Amplication of cDNA Ends） was used to amplify the full length cDNA sequence. Bioinformatics analysis was performed to analysis its function. Results A differentially expressed cDNA fragment expressed lower in gastric cancers and premalignant lesions,no homology was found to known gene sequences in GenBank. The novel cDNA fragment was given an accession number of EST （CD454989）in GenBank. A full length cDNA sequence of 1362bp was acquired, who coded 267 amino acids, and was homologous with BAA91562.1, whose physiology function was unknown. Conclusion One differentially expressed gene was found and it might be involved in process of the gastric carcinogenesis and development.

Key words: Gastric cancer, Premalignant lesions, mRNA differential display, GP1 gene, Northern hybridization