Expression of pJNK in the rat spinal dorsal horn on postoperative day (POD) 10. A, L5 spinal nerve ligation (SNL) induced a remarkable c-Jun N-terminal kinase phosphorylation (pJNK) up-regulation in the ipsilateral lumbar spinal dorsal horn. B, expression of pJNK in the contralateral lumbar spinal dorsal horn. C and D, expressions of pJNK in the ipsilateral lumbar spinal dorsal horn in Sham-Saline and naïve groups. E, up-regulation of pJNK in the ipsilateral lumbar spinal dorsal horn after SNL. F, a high-magnification image from the rectangle area of E shows a high density of pJNK-immunoreactive staining in the ipsilateral lumbar spinal dorsal horn after SNL. G, statistical analysis of pJNK expression in different groups. * indicates a statistically significant difference (P < 0.05) between groups. Six rats in each group. Scale bars: 200 μm in A and B, 100 μm in C, D and E, 20 μm in F.