PCI 34051 is a potent histone deacetylase (HDAC) 8 inhibitor (IC50 = 0.01 μM) with >200-fold selectivity over HDAC isoforms 1, 2, 3, 6, and 10 (IC50s = 4, >50, >50, 2.9, and 13 μM, respectively).PCI 34051 induces caspase-dependent apoptosis in cell lines derived from T-cell lymphomas or leukemias (GI50s = 2.4 - 4 μM), but not in other hematopoietic or solid tumor lines.This compound has also been used to support a critical role for HDAC8 in the coordinated deacetylation of the core cohesion component SMC3 during mitosis.