Retraction

Buschmann et al. (Cell 101, 753–762) reported that Mdm2 is sumoylated at lysine 446 and that this event is important in Mdm2's ability to mediate degradation of p53. Subsequently, we found that K446 is not the site of Mdm2 sumoylation (Erratum published in Cell 107, 549). Additional experiments we performed since then have revealed difficulties in reproducing the data as reported in Buschmann et al., and we can no longer substantiate the major conclusions presented in the paper. Thus, we wish to retract the entire paper and its conclusions in order to avoid wasted efforts by other investigators whose studies might be influenced by the results or conclusions reported in Buschmann et al. We deeply apologize to our colleagues for any confusion that this publication might have caused.