Therapeutically, one of the potentially most promising methyl-inactivated degrons has been described for kruppel like factor 4 (KLF4), which was initially identified as a tumor suppressor in many types of cancers, including gastrointestinal, esophageal, lung, and pancreatic cancer, but later found to be a mitogenic factor in breast cancer and squamous cell carcinoma43. Here, KLF4 is linked to cancer.