Importantly, multiple de-acetylases (histone deacetylases 1, 2, and 3 (HDAC1/2/3) and SIRT1) actively counteract the acetyltransferase activity of p53 co-activators and can therefore inhibit p53 transcriptional activity and tumour suppressive functions [194,195]. This evidence concerns the gene HDAC1 and neoplasm.