CXCR1, also known as IL-8RA and CD181, is an approximately 60 kDa 7TM glycoprotein that functions as a receptor for the chemokine CXCL8/IL-8. It is expressed on neutrophils, monocytes, CD8 T cells, FoxP3+ CD4 Treg cells, mast cells, neuronal and glial cells, vascular endothelial cells, and melanoma. CXCR1 forms homodimers and heterodimers with CXCR2/IL-8RB. It can be cleaved from neutrophils in the lungs of cystic fibrosis patients to release fragments that promote CXCL8 production from airway epithelial cells. CXCR1 mediates neutrophil activation and chemotaxis to sites of inflammation as well as angiogenesis and melanoma invasiveness.