GCP-2 (granulocyte chemotactic protein-2) is a CXC chemokine. Among human CXC chemokines, GCP-2 is most closely related to ENA-78. The structure and sequence of the genes for human GCP-2 and ENA-78 also exhibit close similarity, suggesting the two genes may have originated from a recent gene duplication. LIX (LPS-induced CXC chemokine) was initially cloned as a gene induced by LPS in mouse fibroblasts. The mouse protein designated GCP-2, because of its amino acid sequence similarity (60%) to human GCP-2, is identical to the LIX protein sequence.