For instance, although valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, has been shown to induce cell death in NB cells and overcome hypoxia-induced resistance to cisplatin[101], it has also been reported that VPA treatment increases the percentage of CD133+ NB-CSCs and does not induce apoptosis in these cells. The gene discussed is HDAC9; the disease is neuroblastoma.