These can be hijacked in cancer cells to promote tumorigenesis, with breast and colorectal cancer cells found to exhibit increased levels of the H3K27Ac mark of epigenetic activation at super-enhancer sites of known oncogenes, such as c-Myc and ESR1 (encoding oestrogen receptor α (ERα)), relative to non-malignant tissue as determined by ChIP-seq [163]. Here, ESR1 is linked to cancer.