HDAC9 and glioblastoma: Acting as an HDAC inhibitor at significantly high amounts (millimolar), valproic acid acts as a down regulator of peroxisome proliferator-activated receptors (PPAR), endorsing growth arrest, differentiation, and cell death in many types of genetic alterations of hemopoietic and non-hematopoietic origin, along with glioblastoma, melanoma, breast cancer, and lung cell lines, either alone or in combination with other chemotherapeutic agents (Fig. 3) [80, 81].