HDAC inhibitors also increase the expression of genes that are involved in regulation of ERK/AP-1 signaling, for example the growth associated protein-43 (GAP-43) and Bcl-2, and hence they might increase growth of some cancer cells, e.g., in SH-SY5Y neuroblastoma cells or immature cortical neuroblasts in GAP-43−/− mice [65,101]. Here, HDAC9 is linked to cancer.