CXCR4 and fibrosis: In a murine heterotopic tracheal transplant model with tracheal obliteration by granulation tissue and other murine bleomycin-associated fibrosis models, Cxcl12-inhibition resulted in an attenuation of fibroblastic trafficking/migration, which underlines the importance of the Cxcl12/Cxcr4 axis for generating a profibrotic pulmonary microenvironment [18, 28, 29].