Figure 3. USP7 promotes p53 DNA-binding in vivo.

H1299 cells were either transfected with an empty plasmid (Vector) or transfected with a p53-expressing plasmid alone or in combination with constructs expressing either WT myc-tagged USP7 (+USP7 WT) or myc-tagged C223S (+C223S). p53 occupancy of various promoters in transfected cells was measured by chromatin immunoprecipitation using a p53 antibody and Q-PCR of the target sequences indicated. GAPDH was used a negative control region for Q-PCR. Results were normalized to p53 levels determined for each sample by Western blotting (see Figure 4B for an example) to adjust for any small variations in p53 levels.