To confirm the hypothesis that overexpression of miR-561-3p could downregulate the expression of ZEB1, MYC, and HIF1A genes in BC cell lines, the miR-561-3p or scrambled oligonucleotide was transfected into MDA-MB-231, BT-549, and MCF-7 cells, and the level of MYC, HIF1A, and ZEB1 mRNA was measured by quantitative real-time PCR (Fig. 3, P < 0.01). The gene discussed is HIF1A; the disease is breast cancer.