The chemokine CC ligand 13 (CCL13), also known as monocyte chemotactic protein 4 (MCP-4), is a small molecule cytokine in the CC chemokine family. Its gene is located on human chromosome 17 in a large cluster of other CC chemokines.CCL13 chemotaxis monocytes, eosinophils, T-lymphocytes, and basophils by binding to cell-surface G-protein-linked chemokine receptors, such as CCR2, CCR3, and CCR5.CCL13 activity is involved in allergic reactions such as asthma. Inflammatory cytokines such as IL-1 and TNF-α induce CCL13.