Growth-regulated alpha protein (CXCL1,KC), is a member of the alpha chemokine subfamily, was initially identified as an immediate early gene induced in mouse fibroblasts by platelet-derived growth factor. The N-terminal processed form KC(5-72) of the protein is produced by proteolytic cleavage after secretion from bone marrow stromal cells, and shows a highly enhanced hematopoietic activity. Mouse KC shows approximately 63% identity to that of mouse MIP-2. KC is also approximately 60% identical to the human GROs. It has been suggested that mouse KC and MIP-2 are the orthologs of the human GROs and rat CINCs. Cxcl1 has chemotactic activity for neutrophils, and contributes to neutrophil activation during inflammation. Hematoregulatory chemokine, in vitro, suppresses hematopoietic progenitor cell proliferation.