“…The 18 human HDACs may be classified as either zinc-or NAD 1 -dependent and further subclassified into class I (HDAC1, 2, 3, and 8), class II (HDAC4, 5, 6, 7, 9, and 10), class III (including NAD 1 -dependent sirtuins), and class IV (HDAC11) HDACs. As HDACs regulate a wide variety of processes involved in carcinogenesis, multiple mechanisms may explain the clinical activity of HDAC inhibitors [249,250], including altered gene expression of cell-cycle and apoptotic regulatory proteins [251][252][253][254][255], acetylation of nonhistone proteins regulating cell growth and survival [256][257][258][259], angiogenesis [260,261], aggresome formation [262], and DNA repair [263]. In addition, HDAC inhibitors may have important effects on the tumor microenvironment via reactive oxygen species [264,265], enhanced antigen presentation [266] and downregulation of immunomodulatory cytokines, like IL-10 [267].…”