MIP1 alpha and MIP1 beta were originally co-purified from medium conditioned by an LPS-stimulated murine macrophage cell line. Human MIP1 beta refers to the products of several independently cloned cDNAs, including Act2, PAT 744, hH400, G26, HIMAP, HC21, and MAD 5a. The predicted protein products of these cDNAs represent variants that are between 94% - 98% identical and these proteins are all approximately 75% homologous to murine MIP1 beta. MIP1 beta also shares approximately 70% amino acid