Trichostatin A is an organic compound that serves as an antifungal antibiotic and selectively inhibits the mammalian histone deacetylase family of enzymes. TSA inhibits the eukaryotic cell cycle during the beginning of the growth stage. TSA can be used to alter gene expression by interfering with the removal of acetyl groups from histones and therefore altering the ability of DNAtranscription factors to access the DNA molecules inside chromatin. Thus, TSA has some uses as an anti-cancer drug. By promoting the expression of apoptosis-related genes, it may lead to cancerous cells surviving at lower rates, thus slowing the progression of cancer.