Among them, CXCR2, a chemokine receptor closely related to PPBP and CXCL1 in the development of AF and CKD, is a G-protein-coupled receptor (GPCR) and plays an important role in the human immune system, especially in cell chemotaxis, inflammatory responses, and tumorigenesis. The gene discussed is CXCL1; the disease is atrial fibrillation.