FIG. 4.

Methylation status of the CTCF-binding site in erythroid and nonerythroid cell lines. Genomic DNA from HD3 and DT40 cells was bisulfite treated and amplified in a nested reaction with the primers SRbisF1 plus SRbisR1 and SRbisF2 plus SRbisR2 (see the scheme at the top of the figure). The amplified fragment covered a 200-bp region, which included the five CpG dinucleotides of the CTCF-binding site plus four downstream CpGs (labeled in boldface type). The amplified DNA fragment was cloned and sequenced as described in Materials and Methods. The results of bisulfite sequencing (analysis of 14 clones in each case) are shown at the bottom of the figure. Methylated and unmethylated CpGs are shown as filled or open circles, respectively.