The CpG island of the CXCL12 gene. (A) The CpG island is inside an area from -2594 to +853 (data of the CpGPlot program). The vertical lines correspond to the CpG dinucleotides. The numbers above correspond to the distance in relation to the +1 (TSS). The area considered with promoter activity is outlined and it corresponds to the position -1010 to +122 . (B) Twenty-seven dinucleotides are represented in the figure and positioned in scale. Its localization is signaled below in the figure and the distance in relation to the +1 (TSS). The ERE factor binding is located 19 nucleotides upstream to the CpG island 4 in nucleotides -1900 to -1918. (C) Twenty-seven dinucleotides are numbered in agreement with the sequence. The open circles represent the unmethylated dinucleotides while the dark portion represents the percentage of methylation. On the right side methylation pattern are represented according to data of RT-PCR and the absolute percentage value. The MSP primers for the condition M (methylated) and U (unmethylated) for this island are located below in the figure. (D) Representative examples of sequenced tumours. On the right the methylation percentage of three primary tumours is represented. Global % is the number of methylated CpGs divided by the total analyzed.