To further determine that miR-17 and miR-20b attenuated breast cancer cell resistance to taxol was involved in repressing NCOA3, MCF-7/Tax1 and 231/Tax1 cells were co-transfected with miR-17 or miR-20b mimics along with NCOA3 overexpression constructs, subsequently cells were treated with taxol. This evidence concerns the gene NCOA3 and breast cancer.