transcription factors has shown that highly conserved bromodomains are essential for protein to bind to acetylated lysine. This suggests that specific histone site acetylation has a regulatory role in gene transcriptional activation. Human diseases Inflammatory diseases Gene expression is regulated by histone acetylation and deacetylation, and this regulation is also applicable to inflammatory genes. Inflammatory lung diseases are characterized by expression of specific inflammatory genes such as NF-κB and AP-1 transcription factor. Treatments with corticosteroids and theophylline for inflammatory lung diseases interfere with HAT/HDAC activity to turn off inflammatory genes. Specifically, gene expression data demonstrated increased activity of HAT and decreased level of HDAC activity in patients with Asthma. Patients with chronic obstructive pulmonary disease showed there is an overall decrease in HDAC activity with unchanged levels of HAT activity. Results have shown that there is an important role for HAT/HDAC activity balance in inflammatory lung diseases and provided insights on possible therapeutic targets. Cancer Due to the regulatory role during transcription of epigenetic modifications in genes, it is not surprising that changes in epigenetic markers, such as acetylation, can contribute to cancer development. HDACs expression and activity in tumor cells is very different from normal cells. The overexpression and increased activity of HDACs has been shown to be characteristic of tumorigenesis and metastasis, suggesting an important regulatory role of histone deacetylation on the expression of tumor suppressor genes. One of the examples is the regulation role of histone acetylation/deacetylation in P300 and CBP, both of which contribute to oncogenesis. Approved in 2006 by the U.S. Food and Drug Administration (FDA), Vorinostat represents a new category for anticancer drugs that are in development. Vorinostat targets histone acetylation mechanisms and can effectively inhibit abnormal chromatin remodeling in cancerous cells. Targets of Vorinostat includes HDAC1, HDAC2, HDAC3 and HDAC6. Carbon source availability is reflected in histone acetylation in cancer. Glucose and glutamine are the major carbon sources of most mammalian cells, and glucose metabolism is closely related to histone acetylation and deacetylation. Glucose availability affects the intracellular pool of acetyl-CoA, a central metabolic intermediate that is also the acetyl donor in histone acetylation. Glucose is converted to acetyl-CoA by the pyruvate dehydrogenase complex (PDC), which produces acetyl-CoA from glucose-derived pyruvate; and by adenosine triphosphate-citrate lyase (ACLY), which generates acetyl-CoA from glucose-derived citrate. PDC and ACLY activity depend on glucose availability, which thereby influences histone acetylation and consequently modulates gene expression and cell