BMI1 and neoplasm: To demonstrate the functions of Bmi-1 and miR-27a/miR-155 in tumor growth, metastatic colonization and drug resistance, BGC823-NC mimic, BGC823-miR-155 mimic, BGC823-miR-27a mimic, BGC823-shcon, BGC823-shBmi-1, BGC823-shcon+NC mimic, BGC823-shBmi-1 + miR-155 mimic and BGC823-shBmi-1 + miR-27a mimic cells were injected subcutaneously or intravenously into nude mice.