Figure 4.

Lack of DNA methylation spreading from methylated endogenous retrovirus copies into gene transcription start sites. The cartoons show four examples of ERVs relative to the genes studied and further information can be found in Additional file 2. Only CpGs present in the gene promoter or close flanking region are shown, for the methylated ERV copies please refer to Figure S2 in Additional file 3. bp: base pairs; CGI: CpG Island; ERV: endogenous retrovirus; ES: embryonic stem; LTR: long terminal repeat.