HDAC9 and colonic neoplasm: Moreover, the co-treatments with 5-FU and two inhibitors of histone deacetylase (HDAC), either Vorinostat or LBH589, decrease either the amount of cells in the G1 or S phase together with a inhibition of TYMS gene expression in colon cancer cells (HCT-116 and HT-29), therefore enhancing the effect of 5-FU [14].