Figure 2 - MMP-9 is both necessary and sufficient for neuropathic pain symptoms.
From the following article
Yasuhiko Kawasaki, Zhen-Zhong Xu, Xiaoying Wang, Jong Yeon Park, Zhi-Ye Zhuang, Ping-Heng Tan, Yong-Jing Gao, Kristine Roy, Gabriel Corfas, Eng H Lo & Ru-Rong Ji
Nature Medicine 14, 331 - 336 (2008) Published online: 10 February 2008
doi:10.1038/nm1723
(a) Persistent infusion of an MMP-9 inhibitor via an osmotic pump delays the development of mechanical allodynia in SNL rats. (*P < 0.05 compared to corresponding vehicle control, n = 6). BL, baseline. (b) Reversal of mechanical allodynia by endogenous MMP-9 inhibitor TIMP-1 in SNL rats (*P < 0.05 compared to saline, n = 6). (c) Pretreatment with Mmp9 siRNA (2 
5 
g, i.t.) delays the development of mechanical allodynia in SNL rats (*P < 0.05 compared to respective mismatch control RNAs, n = 9). Inset, gelatin zymography showing knockdown of MMP-9 but not MMP-2 by Mmp9 siRNA in the DRG on SNL day 1. (d) Intrathecal administration of MMP-9 induces rapid but reversible mechanical allodynia in rats (*P < 0.05 compared to saline control, n = 12). (e) MMP-9 null mice show a reduction in SNL-induced spontaneous pain at early times (*P < 0.05 compared to wild-type mice, n = 6). (f) MMP-9 null mice show a reduction of mechanical allodynia at early times after SNL (*P < 0.05 compared to wild-type mice, n = 6). Inset, gelatin zymography showing absence of MMP-9 in MMP-9 null mice. All data are mean 
s.e.m.