C-C Motif Chemokine Ligand 4 (CCL4) is a 7.66 kDa cytokine with 69 amino acid residues. CCL4, also named macrophage inflammatory protein-1beta (MIP-1beta), is mainly secreted from neutrophils, monocytes, B cells, T cells, fibroblasts, endothelial cells and epithelial cells. CCL4 recruits various immune cells like natural killer cells, monocytes, and neutrophils when CCL4 binds to CCR5. In addition, CCL4 mediates lymphocyte adhesion by Rac1 /Cdc42 signaling pathway and plays critical roles in different biological functions like maintenance of cell polarity, regulation of calcium ion transport and response to viruses.