Much interest surrounds the therapeutic use of histone deacetylase (HDAC) inhibitors for virally driven cancers, as there is evidence that HDAC inhibitors downregulate the expression of viral oncoproteins [146], sensitize cancer cells to antivirals [147], activate apoptosis [146,148,149], and spur lytic reactivation [147,150,151] (Figure 3). This evidence concerns the gene HDAC9 and cancer.