ChIP analysis of RUNX1-ETO binding to the SFRP1 promoter. (A) Schematic representation of the genomic structure of human SFRP1 gene. The locations of the consensus RUNX binding site (5′-ACCGCA-3′) on the SFRP1 promoter and the 2 oligos used in ChIP analysis are shown. Shaded boxes represent the 3 coding exons (E1-E3), and vertical bars indicate the predicted promoter CpG island. Horizontal lines below the figure indicate the promoter deletions analyzed in Figure 5. The first nucleotide of start codon is assigned as +1. (B) Chromatin from t(8;21)–positive Kasumi-1 and t(8;21)–negative THP-1 cells was immunoprecipitated with the indicated Abs. PCR was performed with oligo 1 primers designed to amplify DNA sequences surrounding the RUNX binding site on the SFRP1 promoter. Oligo 2 primers were designed to amplify a distal region of the SFRP1 gene lacking RUNX site to evaluate the specificity of protein binding. Amplification of β-globin DNA served as a control for nonspecific precipitated sequences.