These two receptors have mutual relationship and interaction with the ligand CXCL12, resulting in the CXCL12/CXCR4/CXCR7 axis which seems to have several roles in atherosclerosis spanning from proatherogenic and prothrombotic to proinflammatory actions modulated by several factors, as reviewed elsewhere [34]. The gene discussed is CXCL12; the disease is atherosclerosis.