The ectopic expression of miR-33b downregulated the expression of ADAM9, HMGA2, LDHA, SALL4, SNAI2 and Twist1 by more than 30% but had minimal effects on HIF-1α, RAC1, Yes1 and ZEB1 in these two breast cancer cell lines (Fig. 2A,B). This evidence concerns the gene RAC1 and breast cancer.