Panobinostat is a pan-HDAC inhibitor of Class I, II and IV histone deacetylases (HDACs) involved in the deacetylation of histone and non-histone cellular proteins. Panobinostat inhibits purified total cellular histone deacetylase activity (IC50 = 0.03 uM) and activities of most HDAC isoforms (IC50 <10nM). In addition, panobinostat induces expression of the cell-cycle control genes including CDKN1A (p21), and selectively inhibits the proliferation of a variety of tumor cells compared to normal cells. It has been extensively profiled for its in vitro and in vivo pharmacological activity on a variety of tumor cell lines and tumor xenograft mice models.