MUC5B and pulmonary fibrosis: Moreover, since small airways have been implicated in the pathogenesis of diseases that lack large animal models such as asthma, chronic obstructive pulmonary disease (COPD), and MUC5B promoter variant rs35705950-related idiopathic pulmonary fibrosis (IPF), it would be important to translate this methodology to study humans with these diseases (65, 66).