Although CXCL8 is the most commonly studied ligand of CXCR2 in breast cancer, other CXCR2 receptor agonists, such as GRO-α, GRO-β, GRO-γ and CXCL5, are co-regulated with CXCL8. The gene discussed is CXCL1; the disease is breast carcinoma.