Monokine with inflammatory and chemokinetic properties. (www.uniprot.org) Recombinant mouse Macrophage Inflammatory Protein-1 beta produced in E.coli is a single, non-glycosylated, polypeptide chain containing 69 amino acids and having a molecular mass of 7808 Dalton. Macrophage Inflammatory Proteins (MIP) belong to the family of chemotactic cytokines known as chemokines. In humans, there are two major forms, MIP-1alpha and MIP-1beta that are now officially named CCL3 and CCL4 respectively. Both are major factors produced by macrophages after they are stimulated with bacterial endotoxins. They activate human granulocytes (neutrophils, eosinophils and basophils) which can lead to acute neutrophilic inflammation. They also induce the synthesis and release of other pro-inflammatory cytokines such as interleukin 1 (IL-1), IL-6 and TNF-alpha from fibroblasts and macrophages. The genes for CCL3 and CCL4 are both located on human chromosome 17.