<p>Most members of this family of low-molecular weight proteins seem to havemitogenic, chemotactic or inflammatory activities. They are released by phagocytes, mesenchymal cells and a wide variety of tissue cells, upon exposure to inflammation [<cite idref="PUB00001646"/>]. These small cytokines are also called intercrines or chemokines. They are cationic proteins of 70 to 100 amino acid residues that share four conserved cysteine residues involved in two disulphide bonds.</p><p>The family can be split into two groups, depending on the spacing of two N-terminal Cys residues: in one group (CxC), the cysteines are separated by asingle amino acid; in the second (CC), they are adjacent [<cite idref="PUB00001373"/>]. The CxC group includes such factors as interleukin-8, platelet factor 4, melanoma growth stimulatory activity protein, macrophage inflammatory protein 2, platelet basic protein, and several others. The 'C-C' group includes the monocyte chemotactic proteins, macrophage inflammatory proteins, amongst others.</p>