In this regard, the observation that cancer cells have lost monoacetylated lysine 16 histone H4 (Fraga et al, 2005) implies a new molecular pathway that may explain the beneficial effects of HDAC inhibitors because these compounds may promote the restoration of normal histone H4 acetylation levels in the whole cell, restoring the normal chromatin status of repetitive DNA sequences (Fraga et al, 2005). Here, HDAC9 is linked to cancer.