SIRT1 and colorectal neoplasm: This showed that colorectal tumours were distinguished as a group from normal colorectal tissues by the expression of HDAC1, HDAC5, HDAC7A, SIRT1, and SUV39H1. In pairwise comparisons, all colorectal cancers showed significantly lower expression (P < 0.001) of HDAC1, HDAC5, and SIRT1,than their respective normals, except for two colorectal tumours showing higher expression of HDAC5. Higher expression of HDAC7A and SUV39H1 was observed in most colorectal tumours.