In line with p21’s “antagonistic duality” [51], its overexpression leading to its oncogenic activity is found in a variety of human cancers including breast cancer, renal cell carcinoma, testicular cancer, hepatocellular carcinoma, multiple myeloma, gliomas, prostate cancer, cervical carcinoma, ovarian cancer, acute myeloid cancer, esophageal squamous cell carcinoma and soft tissue sarcomas [2,157]. The gene discussed is CDKN1A; the disease is hereditary clear cell renal cell carcinoma.