ENA-78 is a CXC chemokine that was originally isolated from media conditioned by the growth of a mouse lung type-II alveolar epithelial cell line (A549) stimulated by IL-1 or TNF. The full-length cDNA encodes a 114 amino acid (aa) residue precursor protein with a 36 aa residue signal peptide that is cleaved to generate the 78 aa residue secreted protein. ENA-78 shares significant amino acid sequence identity with NAP-2 (53%), GRO,, and (52%, 48% and 51%, respectively), and IL-8 (22%). The gene for ENA-78 has been mapped to chromosome 4q13-q21. Like other CXC chemokines, ENA-78 is a neutrophil attractant and activator in vitro. Based on cross-desensitization experiments, it has been suggested that ENA-78 activity can be mediated through the IL-8 receptor system.