Summary of DNA methylation profiling of the HMEC model system. (A) The DNA methylation profile of the 813 identified DMRs in HMEC (light blue) and early and late vHMEC (orange and red, respectively). Loci hypermethylated in early vHMEC typically exhibit a similar profile in the late vHMEC time point despite extended time in culture. (B) A further 286 regions exhibited stable hypomethylation in the vHMEC samples. (C) ChIP-seq profiling was used to annotate the HMEC genome into eight categories based on the profile of H3K4me3, H3K27ac, H3K36me3 and H3K27me3 including four classes of promoter, regions of predicted transcriptional activity, putative enhancers and polycomb repressed loci. (D) Hypermethylated DMRs were frequently found at regions of predicted low activity such as Promoters 2 and 3, bivalent promoters and polycomb repressed loci as well as putative enhancers. Hypomethylated DMRs predominately affected regions of predicted high activity, such as promoters (Promoter_1) and putative enhancers.