Surprisingly, even though the p53LCs could still bind to and be ubiquitinated by MDM2 in cancer cells (Supplementary Figure S5A, D, and H), they were not degraded by this E3 ubiquitin ligase, as their half-lives were not reduced even in the presence of ectopic MDM2 (Supplementary Figure S5B, C, F, and G). This evidence concerns the gene MDM2 and cancer.