Phosphorylation of SIRT-1 by Cyclin/Cdk1 causes SIRT-1 overexpression in the cell cycle and increases the proliferation of malignant cells in adult T-cell leukemia-lymphoma (ATL), playing a critical role in pathogenesis of this disease.44,51 (Figure 2.E) (Table 1). The gene discussed is SIRT1; the disease is adult T-cell leukemia/lymphoma.