It can be concluded that in tumor cells exposed to HDACs inhibitors pro-apoptotic genes involved in the extrinsic (TRAIL, DR5, FAS, FAS-L, and TNF-α) and/or intrinsic apoptotic pathways (BAX, BAK and APAF1) are up-regulated, while anti-apoptotic genes (Bcl-2 and XIAP (X-linked inhibitor of apoptosis protein)) are downregulated [10]. Here, XIAP is linked to neoplasm.