PURPOSE: In order to elucidate the roles of the cell cycle control genes in the carcinogenesis of Korean gastric cancer, the expressions of cyclin A, Dl, E, p16INK4a and Rb in Korean gastric cancer cells were investigated in this study. MATERIALS AND METHODS: The expression patterns of major cell cycle control genes in Korean gastric cancer cells (SNU1, 5, 216, 484, 601, 620, 638, 668, 710) were analysed by using western blot and reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: In most of the gastric cancer cells investigated, the overexpressions of cyclin A and hyperphosphorylated Rb, and markedly decreased expression of p16INK4a were observed. Over-expression of cyclin E was also observed in SNU1, 484, 601 and 638 gastric cancer cells. CONCLUSION: Considering all these findings, the following model of the gastric catcinogenesis caused by the altered expressions of the cell cycle control genes can be postulated: over-expressions of cyclin A and E cause acceleration of Rb phosphorylation, inactivation of Rb functions and acceleration of Gl/S transition of the cells; decreased expression of pl6INK4a causes inadequate inhibition of cyclin-CDK and further acceleration of Rb phosphorylation; consequently, Rb inactivation, Gl shortening, inappropriate cell division and decreased function of the maintenance of genomic stability occurs. All these abnormalities should contribute to the carcinogenesis of Korean gastric cancer cells.