Furthermore, the effects of MMP-2 and ADAMTS-4 are additive in degrading brevican [247], which may offer one plausible explanation for the ability of exogenous ADAMTS-4 to degrade PNNs in amyotrophic lateral sclerosis model SOD1G93A mice in which PNN breakdown had already occurred, but not WT mice [262, 263]. The gene discussed is ADAMTS4; the disease is amyotrophic lateral sclerosis.