One of a number of chemotactic cytokines. Alpha chemokines are small polypeptides released by macrophages, endothelial cells, keratinocytes, fibroblasts, and smooth muscle cells in the presence of infection or physical tissue damage. In a therapeutic setting, these agents may act as chemoattractants to recruit neutrophils and T cells from the blood to sites of infection or damage and may either promote or inhibit tumor growth by modulating tumor-associated angiogenesis and metastasis. Also known as CXC chemokines. (NCI04)