SIRT1 and breast cancer: In addition to somatic mutations, histone modifying genes are often found to be over- or underexpressed in the context of cancer, such as EZH2 overexpression in prostate, bladder, ovarian, and breast cancer, MLL1 overexpression in colon cancer, and SIRT1 overexpression in prostate and colon cancer and downregulation in breast cancer and hepatic cell carcinoma (24–29).