Methylation pattern of the proximal IL-1α promoter and of intron IV in naive T cells. DNA from naive T cells was treated with bisulfite, and different parts of the promoter (CpGs –7 through –1, left) and intron IV (CpGs +17 through +29, right) were amplified by PCR and cloned. From each region, multiple clones were sequenced. Each circle represents a CpG and is numbered relative to the transcription start site.