Figure 5.

Gene expression data. Histograms illustrating gene expression of (a) nerve growth factor (NGF) and (b) substance P in postmortem (PM) normal, PM degenerate and surgical degenerate human intervertebral disc. Relative gene expression was normalised to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and plotted on a log scale. **P < 0.01. Scatterplots illustrating correlations in (c) NGF versus matrix metalloproteinase-10 (MMP-10) expression and (d) NGF versus substance P expression in surgical degenerate samples.