In contrast, SIRT2 was also observed to be tumor-suppressive: Kim et al found that aged SIRT2 knockout mice have increased tumor incidence compared with WT controls 39; Fiskus et al. demonstrated that SIRT2 inhibits the peroxidase activity of peroxiredoxin, and thus sensitizes breast cancer cells to intracellular DNA damage and cell death 40. The gene discussed is SIRT2; the disease is breast cancer.