Moreover, the concentration of CXCL12 in the plasma of patients with idiopathic pulmonary fibrosis was significantly higher than in healthy controls [29], suggesting that circulating fibrocytes are recruited through the CXCR4 - CXCL12 axis and contribute to lung fibrosis in this patient population. Here, CXCL12 is linked to idiopathic pulmonary fibrosis.