hCGBP fails to bind to methylated CpG motifs. EMSA was performed as described in Materials and Methods, using either the CpG-pos or CG11 oligonucleotide as the probe. Purified histidine-tagged hCGBP fusion protein (720-bp cDNA fragment) (0.5 μg) or 3 μg of heparin-fractionated nuclear extract derived from <t>K562</t> cells was added where indicated. Probes were methylated by Sss I methylase as described in Materials and Methods. The arrows indicate the positions of retarded EMSA complexes.