DDX5 and breast cancer: In order to assess the extent to which Ddx5 and Ddx17 participate in gene expression regulation in response to estradiol (E2), ER-positive MCF-7 breast cancer cells were treated with E2 or vehicle for 10 h after being transfected with a control siRNA (siCTRL) or an siRNA (siDdx5/17) targeting a conserved region shared by Ddx5 and Ddx17 (Figure 1A).