However, SDF‐1 also can be secreted by pulmonary fibroblasts and alveolar epithelial type II cells (AEC II), leading to activation and recruitment of CXCR4‐ positive cells.[24] CXCR4 is abundantly expressed in IPF patients, with prominent expression in honeycomb cysts and the distal airway epithelium.[25] CXCR4 inhibition attenuates the progression of bleomycin (BLM)‐induced pulmonary fibrosis in mice.[12a]. Here, CXCR4 is linked to idiopathic pulmonary fibrosis.