Chemokine ligand 4 (CCL4), also known as macrophage inflammatory protein 1β (MIP-1β), is a CC chemokine with specificity for the CCR5 receptor. It chemotaxis natural killer cells, monocytes, and a variety of other immune cells and can be induced to be expressed by many cell types in mice, including mast cells, endothelial cells, macrophages, and CD8+ T cells. The mouse CCL4 cDNAs encode a 92 amino acid residue precursor protein containing a 23 amino acid residue signal peptide, and cleavage of this precursor protein produces a 69 amino acid residue secreted mature protein.CCL4 is an important HIV suppressor produced by CD8+ T cells. Chemokine activity is regulated by G-protein-coupled seven times transmembrane structural domain receptors, CCR1, 5, and 8 These receptors regulate the biological activity of CCL4. In the same cell population, CCL4 is 20-fold weaker in activity than CCL3.