Chemokine (C-X-C motif) ligand 9 (CXCL9), also commonly known as monokine induced by interferon-gamma (MIG), is a small cytokine belonging to the CXC chemokine family and is closely related to two other ELR-negative CXC chemokines: CXCL10 and CXCL11.
There have been 17 different C-X-C chemokines described in mammals that are subdivided into two categories: those with a specific amino acid sequence (or motif) of glutamic acid-leucine-arginine (or ELR for short) immediately before the first cysteine of the C-X-C motif (ELR-positive), and those without an ELR motif (ELR-negative). ELR-positive C-X-C chemokines specifically induce the migration of neutrophils, and interact with chemokine receptors CXCR1 and CXCR2. C-X-C chemokines that lack the ELR motif are chemoattractant for lymphocytes.
CXCL9 (MIG) is a T-cell chemoattractant. Induced by IFN-gamma (IFN-γ), the ELR-negative chemokine CXCL9 (MIG) elicits its effects by binding to the cell surface chemokine receptor CXCR3.