AGO2 and cancer: Du et al. (2016) reported that high levels of circ-Foxo3 expression in non-cancer cells are associated with cell cycle progression. More concretely, aberrant circ-Foxo3 expression represses cell cycle progression by binding to the cell cycle proteins cyclin-dependent kinase 2 (CDK2) and cyclin-dependent kinase inhibitor 1 (P21), which results in the formation of a ternary complex and subsequently blocks cell cycle progression. Chen et al. (2019) found high levels of circ-AGO2 and human antigen R (HuR) expression and associated them with poor outcomes among patients with gastric cancer.