BMI1 and gastric cancer: To explore the miR-27a- and miR-155-mediated regulatory effects of Bmi-1 on RKIP in terms of GC progression, we infected BGC823 and SGC7901 cells with lentiviruses carrying miR-155 mimic, miR-27a mimic, shBmi-1, shBmi-1 + miR-27a mimic and shBmi-1 + miR-155 mimic.