SYK is methylated in cHL cell lines and in HRS cells of primary cHL. The methylation status of the SYK promoter was analyzed by genomic sequencing. The bisulfite-treated genomic DNA was amplified with seminested primers as indicated: FO indicates forward outer primer; FI, forward inner primer; and R, reverse primer. For amplification of DNA from cell lines and normal tissues only FO and R primers were needed (since there was enough material). The obtained amplicon contained 35 CpG dinucleotides. The first and last CpGs were located at positions -294 and -23, respectively, counting from the start site of transcription (bent arrow, predicted by Entrez Gene, NCBI). Samples of 50 to 100 microdissected HRS cells were reamplified with seminested primers FI and R. This amplicon included 29 CpGs; the first CpG was at the position -228. The gray bar represents the CpG island. The first exon is depicted as an open box. The PCR products were cloned into the pCAP^svector and sequenced. Peripheral B lymphocytes (PBLs) PBL1, PBL3, and PBL4 were isolated from the blood of healthy donors. HRS cells were isolated from primary cHL biopsies (HL41, HL61, and HL45) by laser capture microdissection. Clones (5 to 11) were sequenced from each sample. Every row represents a single PCR clone. □ indicates unmethylated CpG dinucleotides; ▪, methylated CpGs.