Abstract: Objective To explore the effects of Rab27B on the proliferation and apoptosis in human MKN-45 cells. Methods Constructed the Lv-Rab27B-EGFP carrier and transferred it to MKN-45 cells as Rab27B group. Set up blank and negative control group. Cell growth was measured by CCK8 assay, the cell cycle and apoptosis were detected by flow cytometry. Relative expression levels of Bax, Bcl- 2 and caspase3 were detected by Western blot. Results Compare to blank and negative control cells, the proliferation of Lv-Rab27B-EGFP MKN-45 cells were decreased（P<0.05）. Flow cytometry showed that over-expressed Rab27B resulted in an increase of G0/G1 phase and apoptotic cells. Expression of pro-apoptotic protein Bax was increased, and that of anti-apoptotic protein Bcl-2 was decreased differentially（P<0.05）, the expression of caspase3 also showed significant difference（P<0.05）. Conclusions Rab27B over-expression can inhibit cell proliferation by regulating cell cycles and induce apoptosis mainly through regulating Bcl-2 and caspase family proteins expression in MKN-45 cells.

Key words: Rab27B , MKN-45, proliferation, cell cycles, apoptosis