For example, HDAC1 and HDAC2 expression levels are moderately elevated in papillary thyroid carcinoma tissues compared with normal tissues.100 Besides, HDAC1 is reported to be expressed in a significant proportion of cancers, such as gastric carcinoma, prostate cancer, lung cancer, breast cancer, and colon cancer101 (Table 1). This evidence concerns the gene HDAC2 and breast carcinoma.