ChIP analysis demonstrates that KLF2 and KLF4 sequester CBP/p300 and decrease CBP/p300-NF-κB complex formation and binding to NF-κB–binding sequences in the E-selectin promoter. Cells were transfected with scrambled DNA or KLF2 or KLF4 expression vectors and then incubated with medium alone or with β₂GPI and anti-β₂GPI antibodies for 5 hours. After formaldehyde treatment, cell lysates were immunoprecipitated with control IgG or anti-CBP/p300 antibodies, and DNA within the immunoprecipitates was isolated and amplified using primers specific for NF-κB–binding sites in the E-selectin promoter. In cells transfected with scrambled DNA, immunoprecipitation with the CBP/p300 antibody coprecipitated DNA that amplified strongly with these primers, suggesting formation of an NF-κB–CBP/p300 complex bound to NF-κB–binding sites in the E-selectin promoter. In contrast, amplification of DNA from CBP/p300 immunoprecipitates of KLF2- or KLF4-transfected cells yielded a signal only slightly increased above the baseline obtained from control cells, suggesting decreased NF-κB–CBP/p300 complex formation and decreased binding of this complex to NF-κB–binding sites in the E-selectin promoter. Control IgG did not immunoprecipitate a sequence that could be amplified. The abundance of each CBP/p300 coprecipitated NF-κB–binding sequence was calculated as fold change relative to the amount precipitated by control IgG.