AR-42, also called OSU-HDAC42, is a powerful inhibitor of histone deacetylase (HDAC). It effectively stops HDAC activity, leading to increased acetylation of histone H3, α-tubulin, and an up-regulation of p21. HDAC inhibitors focus on HDAC enzymes, hindering the growth of cancer cells and triggering apoptosis, the programmed death of cancer cells. Reagent grade, for research purpose.