High levels of expression of HDAC5 and HDAC9 mRNA and protein in primary pediatric medulloblastoma tumors are associated with poor survival; also, transfection with multiple siRNAs for HDAC5 and 9 in established tumor cell lines caused a reduction in cell proliferation in all of the transfection vectors that were studied [48]. The gene discussed is HDAC9; the disease is medulloblastoma.