MUC1 and pulmonary hypertension: Acute exacerbations of IPF are commonly encountered in patients with low Forced Vital Capacity (FVC), Diffusion lung CO (DLCO), low six-minute-walk distance, pulmonary hypertension, poor baseline oxygenation, increased dyspnea and other cardiovascular disease or high body mass index [41], and furthermore, an elevated serum level of Krebs von Lungen-6 (KL-6) [42].