HDAC9 and neoplasm: Such mechanisms have been reported to play important roles in the etiology of cancer and have led to the introduction of the histone deacetylase (HDAC) inhibitors, vorinostat, romidepsin, belinostat, and panobinostat, as inhibitors of tumor proliferation in several types of cancer.42 However, these drugs are pan‐inhibitors of different HDAC types, each with different specificities and functions, so they have pronounced clinical side‐effects.