Covalent modification of the oncogene product Mdm2 by the ubiquitin-related protein SUMO1 protects it from ubiquitination and enhances its E3 ligase activity towards p53 in vitro. Disappearance of ...

The ATM gene (mutated in the disease ataxia telangiectasia) activates the p53 tumor suppressor protein in response to DNA damage, explaining the higher incidence of cancer in AT patients.