For example, HDAC2 and HDAC3 are highly expressed in breast cancer 7, HDAC2 overexpression is negatively correlated with survival in hepatocellular carcinoma (HCC) 8, HDAC5 overexpression may promote the proliferation and differentiation of HCC cells by upregulating the expression of slx1 9, HDAC7 is overexpressed in colon cancer and chronic lymphoid leukemia (CLL) 10, and HDAC2 overexpression in gastric cancer is generally associated with tumor invasion 11. Here, HDAC2 is linked to breast cancer.