WGBS of a normal breast (NB), three primary breast tumors (BT089, BT126 and BT198), a mammary epithelial cell line (HMEC) and two breast cancer cell lines (MCF7 an HCC1954).

<p>(A) Circos representation of genome-wide DNA methylation levels in the seven breast samples. The data represent the average methylation levels for all of the CpGs in 56,779 50 Kb windows. Coloring indicates methylation levels from low (green) to high (red). (B) The proportion of CpG sites in the DNA that were lowly (< 20%), intermediately (20% ~ 80%) and highly (> 80%) methylated in the seven samples. (C) The proportion of CpG sites in the CGI that were lowly (< 20%), intermediately (20% ~ 80%) and highly (> 80%) methylated in the seven samples. (D) Heatmap representation of average methylation levels of 10 Kb windows with different CpG densities. The CpG density was expressed as the number of CpG sites per 100 bp of nucleotide sequence. Coloring indicates methylation levels from low (green) to high (red). (E) The distribution of the DNA methylation levels of CGI in promoter (TSS ± 1 Kb), intragenic and intergenic regions.