Supplementary Figure 2: p53^enh3508 region exhibits a p53-dependent enhancer activity that is required for OIS activation.

(a) Senescence induction was quantified using senescence-associated β-gal assay. (b) MCF-7 cells were transfected with the indicated vectors, treated with Nutlin-3a 5-10 hours later, and harvested 25-30hr after treatment. The relative luciferase activities (Firefly/Renilla) were normalized to the Ctrl reaction. (All p-values for luciferase assay were calculated by Student’s t-test. * indicates the significance relative to empty vector; # indicates the significance relative to untreated matching sample). (c) The same assay as in panel b, only that cells were co-transfected with control, or p53-targeting siRNAs. A reporter vector containing the enhancer region p53-BER4²⁰ was used as a positive control for p53-dependency. The efficiency of p53 knockdown was determined by immunoblot analysis. (All p-values for luciferase assay were calculated by Student’s t-test. * indicates the significance relative to empty vector).