AIM To establish a model system for studying gastric carcinogenesis of MNNG, a gastric cancer relatedcarcinogen.METHODS Cell culture transformation, PCR-restriction fragment length polymorphism (PCR-RFLP),DNA blotting and immunochemical techniques and analysis of LDH isozyme and chromosome wereperformed.RESULTS GES-1 cells surviving by MNNG treatment were named MC (2 × 105M for 24 hours) and MC-B(2 × 10-7M for 7 days). The two cell lines treated by MNNG showed more malignant than maternal cell GES-1 with the evidences of more chromosome aberrations, abnormal morphology and eytoskeleton and alsogained the ability of colony formation on soft agar. C-Ha-ras gene point mutation in the 12th codon and LDHisoenzyme abnormal express were found in MC-B cells. In addition, C-met gene rearrangement was revealedby Southern blot analysis in MC-B and MC.CONCLUSION This gastric epithelial cell system is an important model system for further study of stomachcancer, MNNG had a selective effect on the cytoskeleton mierofilament in human gastric epithelial cells andintimately associated with the activation of certain oncogenes and some protein.