Two mono-conjugates, miR-17–BC-α and miR-17–BC-β, were designed to target miR-17, whereas the other four mono-conjugates, miR-21–BC-α1, miR-21–BC-β1, miR-21–BC-α2, and miR-21–BC-β2, were targeted to miR-21 and differed in the location of the dRα or dRβ relative to the miRNA sequence (Figure 1). The gene discussed is SLC26A3; the disease is breast cancer.