A cell-permeable, non-toxic dioxotetrahydroquinoxaline compound that mimics uridine and directly and reversibly interacts with the microRNA (miRNA) binding domain of Argonaute-2 (Ago2; KD = 126μM) and significantly inhibits binding of miR-20a, miR-26a, miR-107, miR-223, and let-7a to A