Many of these upregulated miRNAs were known oncomiRs in breast cancer, such as miR-200, miR-141 and miR-223 [21–23], Also, many of down-regulated miRNAs in MCF7 HER2 cells were tumor suppressors, such as miR-125b, miR-31 and miR-99a [24–26]. This evidence concerns the gene ERBB2 and breast cancer.