Mouse CCL12 belongs to the CC chemokine family and is most closely related to human CCL2 (MCP-1) in structure (66% amino acid identity). CCL12 binds to cell surface receptor CCR2, a human CCL2 primary receptor, and can induce migration and Ca2+ flux. CCL12 is a potent chemoattractant for peripheral blood monocytes but only has weak activity on eosinophils at high doses. CCL12 is produced by macrophages during early allergic reactions and infections. During murine MCV infection, bone marrow F4/80 (+) cells can produce high levels of CCL12. The expression of CCL12 can also be upregulated by bacterial infections including pneumococcal meningitis and polymicrobial septic peritonitis. LPS can induce the expression of CCL12 in liver macrophages (Kupffer cells) in vivo. CCL12 is involved in the pathogenesis of pulmonary fibrosis by recruiting fibrocytes to the injury site and enhancing fibrotic responses. Also, CCL12 is implicated in liver and kidney fibrosis. It has also been shown that hypoxia inducible factor 1 is involved in hypoxia-induced upregulation of CCL12 in astrocytes. In addition, CCL12 is involved in joint and growth plate development.