Interestingly, miR-92b-3p mimic transfection resulted in down-regulation of circCDYL in both HER2+ and HER2– BC cells, and AGO2 silencing could almost prevent the down-regulation of circCDYL from miR-92b-3p mimic transfection, indicating that circCDYL was degraded in a miR-92b-3p dependent RISC manner. This evidence concerns the gene AGO2 and breast cancer.