CXCR4 and pulmonary fibrosis: Recently, less cytotoxic, more potent, and stable CXCR4 inhibitors such as BL8040 [69] and LY2510924 [70] have been developed, and thus the effects of targeting the CXCL12/CXCR4 axis by CXCR4 inhibitors for the treatment of lung fibrosis should desirably be re-examined.