Chemokine (C-C motif) ligand 7 (CCL7) is a small cytokine known as a chemokine that was previously called monocyte-chemotactic protein 3 (MCP3). Due to CCL7 possessing two adjacent N-terminal cysteine residues in its mature protein, it is classified among the subfamily of chemokines known as CC chemokines. CCL7 specifically attracts monocytes, and regulates macrophage function[citation needed]. It is produced by certain tumor cell lines and by macrophages.This chemokine is located on chromosome 17 in humans, in a large cluster containing many other CC chemokines and is most closely related to CCL2 (previously called MCP1).