SET is part of a complex localized to the endoplasmic reticulum however is found in the nucleus. SET inhibits apoptosis following attack by cytotoxic T lymphocytes and can also enhance DNA replication of the adenovirus genome. SET inhibits acetylation of nucleosomes, particularly histone H4, by histone acetylases (HAT). This inhibition is accomplished by masking histone lysines from being acetylated.