Purity >95% as determined by SDS-PAGE. Macrophage inflammatory protein-1 beta (MIP-1-beta), also known as CCL4, is produced by macrophages and functions as a mitogen-inducible cytokine. MIP-1-beta signals through the chemokine receptor CCR5 to chemoattract immune cells. MIP-1-beta induces inflammatory responses, including neutrophil superoxide production. The MIP-1-alpha and MIP-1-beta heterodimer exhibits antiviral activity against the human immunodeficiency virus 1 (HIV-1).