XBP1 and chronic obstructive pulmonary disease: The platelet differentiation factor, X-box binding protein-1, has a higher level of expression in the lung homogenates, epithelial cells, and bronchoalveolar lavage fluid (BALF) from patients with IPF expressed than in those from patients with chronic obstructive pulmonary disease (COPD) patients and controls [104,105], suggesting that clot-forming responses are continuously activated.