HDAC9 and cancer: For instance, HDAC (histone deacetylase) enzymes which play an essential role in cancer development and progression and HDACIs (HDAC inhibitors) have been found to affect differentiation and cell cycle arrest, activate the apoptosis related extrinsic / intrinsic pathways, prevent metastasis and angiogenesis, and restore the chemotherapy sensitivity in different cancer cell lines including pancreatic cancer.