Recently, we have isolated and characterized a set of cDNA clones which encode lipopolysaccharide-inducible proteins in murine peritoneal macrophages. Here, we report the sequence and identification of one of these cDNAs previously termed C7. Nucleotide sequence analysis revealed an open reading frame encoding a predicted polypeptide composed of 98 amino acids, which contained a 21 amino acid residue signal peptide, indicating approximately 9 kDa of mature protein. The deduced protein sequence showed homology (67% identity, 77% considering conservative amino acid changes) with the human INF gamma-inducible gene IP-10, a member of the recently described superfamily of chemotactic and mitogenic proteins which includes platelet factor 4, monocyte-derived neutrophil chemotactic factor (NAF, NAP-1, IL-8), and MGSA/gro/KC. Thus C7 would appear to represent the murine homologue of the human IP-10 gene or a very closely related gene.