The RARβ2 promoter, containing several high-affinity RA-responsive elements (RAREs), is normally mediated by a dynamic histone deacetylase (HDAC) and histone acetyltransferase (HAT) balance in the presence of physiological levels of RA. However, increased level of histone deacetylation was observed during epithelial cell tumorigenesis and appropriate level of histone reacetylation at RARβ P2 can lead to reactivation of endogenous RARβ2 transcription [44 ].
Source: wiktionary