Fig. 1

Epigenetic mechanisms such as acetylation of histones via histone acetyl transferase enzymes cause flux between euchromatin and heterochromatin. This results in altered gene expression. It is important to note that not all epigenetic enzymes are characterized as either activators or inactivators of transcription. For example, LSD1 can act as both as co-repressor or co-activator of transcription, dependent on the target residue. Cancer genomes utilize epigenetic mechanisms in tumorigenesis