Of the short-chain fatty acid HDAC inhibitor class, valproic acid has been found to exhibit its antineoplastic effects through decreasing the activity and expression levels of matrix metalloproteinases (MMPs) in addition to the inhibition of activity of HDAC class I and II, thereby decreasing the invasiveness of glioblastoma cell lines[69]. The gene discussed is HDAC9; the disease is glioblastoma.