SIRT1 and chronic obstructive pulmonary disease: Compared with healthy subjects, the patients with COPD showed decreased levels of 120-kDa s120S (SIRT1 ratio in healthy subjects [NS + SM], 0.90 ± 0.34 vs subjects with COPD, 0.68 ± 0.24; P = .014) (Fig 2A), whereas SIRT1 with lower molecular weights (102 kDa and 75 kDa) did not (Figs 2B, 2C, e-Figs 1A, 1B, 1C).