HDAC9 and renal cell carcinoma: RCC cell lines with PLCD1 methylation/downregulation were further treated with DNA methyltransferase inhibitor, 5-Aza, either alone or in combination with a histone deacetylase (HDAC) inhibitor, trichostatin A. Cell viability of 80–90% was observed after exposure to this concentration (10 μM) of 5-Aza for 3 days.