Studies have shown that CDK20 and p21Cip1/Waf1 serve as important regulators in tumorigenicity and are functionally connected to a broad range of cell signaling pathways with important functions in cell cycle progression, cell proliferation, and malignant transformation, indicating that these regulators may serve as novel prognostic markers and may be promising candidates as a molecular target for cancer therapy for some types of cancer. This evidence concerns the gene CDKN1A and cancer.