SPARC mRNA expression and DNA methylation in IVDs from chronic LBP patients with disc degeneration. Pain intensity measured with the numeric rating scale (a) and physical disability as determined by the Oswestry Disability Index (b) were increased in surgical patients, as was lumbar disc degeneration based on scoring of MRI images (c). The state of methylation of CG sites in the human SPARC promoter (d) in L4-L5 IVDs was increased as quantified by pyrosequencing (e) * = p < 0.05, ** = p < 0.01, *** = p < 0.001. Two-tailed student t-test. n = 5-8/group. Error bars = S.E.M.