ENA-78 is a CXC chemokine that signals through the CXCR2 receptor. It is expressed in monocytes, platelets, endothelial cells, and mast cells. ENA-78 is a chemoattractant for neutrophils. The three naturally occurring variants of human ENA-78; ENA 5-78, ENA 9-78 and ENA 10-78, contain 74, 70, and 69 amino acid residues, respectively, and possess the same biological activity. ENA-78 contains the four conserved cysteine residues present in CXC chemokines, and also contains the 'ELR' motif common to CXC chemokine that bind to the CXCR1 and CXCR2 receptors. Recombinant human ENA-78 is an 8.0 kDa protein consisting of 74 amino acid residues.