SIRT1 and intervertebral disk degenerative disorder: As shown in Figures 2(a) and 2(b), immunohistochemical results indicated that SIRT1 and LC3B expression was obviously lower in IDD tissues than in LVF tissues, whereas the expression of cleaved caspase 3 (apoptosis-related biomarker) in IDD tissues was significantly higher than that in LVF tissues.