MMP9 and myeloid sarcoma: The studies implicate an important role of especially MMP-9 in MS with results showing increased serum and cerebrospinal fluid (CSF) levels of MMP-9 in patients with MS compared with healthy controls (HCs) and increased MMP-9 CSF levels in RRMS patients during active disease compared with stable RRMS patients (Liuzzi et al., 2002).