To explore the interplay between p53 and DEPTOR, we first examined the protein levels of DEPTOR in multiple cancer cell lines with distinct p53 statuses whose transcriptional activity was confirmed by determining the basal and induced levels of endogenous MDM2 and p21, two well-established p53 target genes, upon exposure to ionizing radiation (IR) to activate p53 (Figure S1A and S1B). Here, MDM2 is linked to cancer.