Plerixafor also significantly reduced the in vitro plasma-induced migration of fibrocytes purified from the blood of exacerbating COPD patients [76], suggesting that the CXCL12-CXCR4 axis could participate to the recruitment of fibrocytes to the lungs during COPD exacerbations [130]. This evidence concerns the gene CXCR4 and chronic obstructive pulmonary disease.