MDM2 and breast cancer: Furthermore, this may serve as a potential therapeutic approach to restore p53 in p53-deficient cancers including those in which MDM2 is overexpressed and those with nonsense/frameshift mutations at the C-terminal end of TP53. We tested our hypothesis using MDM2-overexpressing non–small cell lung cancer (NSCLC) and glioblastoma multiforme (GBM) cells bearing WT p53 and p53 mutant NSCLC and breast cancer and urinary bladder cancer cells as models.