ESR1 and breast cancer: Interestingly, we observed ESR1, a central player in HR+ BC, to be regulated by hsa-miR-17-5p, hsa-miR-18a-5p, hsa-miR-221-3p, and hsa-miR-505-5p (high confidence and experimentally validated), while hsa-miR-934, hsa-miR-545-5p, and hsa-miR-18a-3p were predicted to regulate ESR1 with moderate confidence (Fig. 7B).