Trichostatin A (TSA) is a potent and non-competitive reversible inhibitor of HDAC (histone deacetylase) with a Ki of 3.4 nM. In HeLa cells, Trichostatin A blocked cell cycle progression at G1 and induced a 12-fold increase in intracellular levels of gelsolin.Trichostatin A is a useful tool for induction of hyperacetylation of cellular histones and for further elucidation of their role in gene expression. Trichostatin A is also known as TSA, and [R-(E,E)]-7-[4-(Dimethylamino)phenyl]-N-hydroxy-4,6-dimethyl-7-oxo-2,4-heptadienamide.