Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
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 SUMO-modified Mdm2, which is observed upon radiation, may thus be a prerequisite for DNA-damage-induced accumulation of p53.
The molecular pathways that mediate apoptosis are tightly regulated by a series of positive and negative signals, the balance of which determines whether or not cells commit suicide. New data from several laboratories now show that heat-shock proteins (HSPs) can influence this process through direct physical interaction with key components of the apoptotic machinery. These reports marry the survival (or death)-endowing properties of HSPs to the cell-death pathway.