MUC5B and idiopathic pulmonary fibrosis: Although the precise mechanisms through which MUC5B dysregulation contributes to IPF development are currently unknown, MUC5B overexpression may cause mucociliary dysfunction, retention of particles and disruption of the normal reparative mechanisms in the distal lung, leading to chronic fibroproliferation and regenerative process that results in honeycomb cyst formation [10–14].