The BOB.1/OBF.1 CpG island is methylated in HRS cells of primary cHL. Bisulfite-treated genomic DNA was amplified with seminested primers (FO, FI, and R). The primers were located to amplify the CpG island within exon 1. The amplicon obtained using FI and R primers contained 18 CpG dinucleotides. The first and last CpGs are at positions +183 and +373, respectively, counting from the start of transcription. The filled part of exon 1 indicates the coding sequence. All other symbols are the same as for Figure 5.