MDM2 and cancer: Another example still stemmed from the study of circ-Foxo3 by Du et al. They showed that circ-Foxo3 was minimally expressed in cancer cells and tumor samples and circ-Foxo3 promoted MDM2-induced p53 ubiquitination degradation in the form of circFoxo3-Mdm2-p53 complex to avoid MDM2-induced Foxo3 ubiquitination with low binding affinity, resulting in increased levels of Foxo3 protein [61].