Chemokine (C-X-C motif) ligand 9 (CXCL9) also known as Monokine induced by gamma interferon (MIG) is a small cytokine belonging to the CXC chemokine family. CXCL9 is a T-cell chemoattractant, which is induced by IFN-γ. It is closely related to two other CXC chemokines called CXCL10 and CXCL11, they all elicit chemotactic functions by interacting with the chemokine receptor CXCR3. Matrix metalloproteinase 8 (MMP-8) degrades CXCL9 and cleaves CXCL10 at two positions. Matrix metalloproteinase 9 (MMP-9) degrades CXCL10 and cleaves CXCL9 at three different sites in its extended carboxy-terminal region.