Figure 5. p53 binds to both of the p53 response elements on the SAP promoter. T cells negatively isolated from buffy coat were cultured with PHA (1 µg/ml) for 3 days. Cells were fixed with 1% formaldehyde, sonicated to fragment DNA and immunoprecipitated with antibody-specific against p53 (DO-1) and a non-specific antibody of the same isotype directed against SV40 T antigen. The abundance of precipitated DNA fragments was measured by quantitative PCR using primers specific to p53 RE-1 and p53 RE-2 of the SAP gene. MDM2 served as positive control. Results from three different donors are shown.