Methylation interference assay was performed as described under “Experimental Procedures.” The double-stranded BTE oligonucleotide was labeled at the 5′ end of either the sense or antisense strand. A, is the result of the interference assay. The 5′ end of each strand is shown. The DNA included in lanes 1, 3, 4, and 6 was derived from the unbound free probe, whereas the DNA included in lanes 2 and 5 was from the bound probe. Methylated guanine and adenine residues are identified. B, shows the guanine residues (arrowheads) within the BTE, which when methylated resulted in an interference of binding to GKLF.