Fig. 7. Half-life of Mdm2 mutants. U2OS cells were transiently transfected with plasmids encoding the indicated Mdm2 mutants and then incubated in medium containing [35S]methionine and [35S]cysteine. Cells were harvested at the indicated times after removal of the labeled medium, and the amount of labeled Mdm2 protein immunoprecipitated at each time point was detected by autoradiography.