HDAC9 and nasopharyngeal carcinoma: We treated cells in NPC medium supplemented with recombinant human LIF and a chemical cocktail composed of SB431542 (TGF-β inhibitor), CHIR99021 (GSK3b inhibitor) [35], valproic acid (VPA- an HDAC inhibitor that can significantly improve reprogramming and neural conversion efficiency) [23,28] and purmorphamine (hedgehog signaling agonist, [26])–all referred to M1, for the first 14 days (Fig 2A).