For instance, the cyclin-dependent kinase inhibitors (CDKs), CDKN1A (p21Cip1), CDKN1B (p27Kip1), and CDKN2A (p16Ink4A), reprimo (RPRM), stratifin (SFN), and CDK1 are all frequently hypermethylated and play various roles in tumor radioresistance (140). The gene discussed is CDKN1A; the disease is neoplasm.