GDF-5 overexpression prevents NF-κB over-activation in LPS-stimulated nucleus pulposus cells. (A) Western blotting results for the protein expression levels of p-IκB and p-p65. Quantitative analysis of western blotting data demonstrated that GDF-5 significantly inhibited the phosphorylation of (B) IκB and (C) p65 induced by LPS, indicating that GDF-5 inhibited the activation of the NF-κB pathway induced by LPS. **P<0.01 vs. Ctrl group; #P<0.05 and ##P<0.01 vs. LPS group. GDF-5, growth and differentiation factor-5; LPS, lipopolysaccharide; Ctrl, control; NF-κB, nuclear factor-κB; p, phosphorylated.