This was further supported by other studies where it was shown that CXCR4+fibrocytes were the predominant population of fibrocytes in circulation in IPF patients and that these cells were present in histological sections from human IPF lung biopsies (Mehrad et al., 2007; Andersson-Sjöland et al., 2008). Here, CXCR4 is linked to idiopathic pulmonary fibrosis.