Purpose Epigenetic processes are implicated in cancer causation and progression. The
acetylation status of histones regulates access of transcription factors to DNA and influences
levels of gene expression. Histone deacetylase (HDAC) activity diminishes acetylation of
histones, causing compaction of the DNA/histone complex. This compaction blocks gene
transcription and inhibits differentiation, providing a rationale for developing HDAC
inhibitors.