PEA3 is required for enrichment in Notch-1 and Notch-4 promoter regions. (A) MDA-MB-231 cells were cotransfected with pcDNA3.1-PEA3 expression plasmid and control siRNAa or PEA3 siRNAa. Lysates were subjected to chromatin immunoprecipitation using either PEA3-specific antibody or an isotype control IgG on the Notch-1 and Notch-4 promoters, respectively. PEA3 enrichment was measured by quantitative PCR and normalized to IgG control. Statistical comparisons were performed between PEA3 siRNAa and control siRNAa using a two-tailed, unpaired Student's t-test for two comparisons. (B) Lysates from the experiment described in (A) were subjected to SDS-PAGE followed by Western blot analyses to detect PEA3 protein and actin protein as a loading control. The Western blots are representative of three independent experiments. Error bars represent standard deviations. The statistical significance of three or more experiments was determined by performing a two-tailed, unpaired Student's t-test for two comparisons.