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). Here, CDKN1B is linked to neoplasm.