MUC5AC and airway hyperresponsiveness: Recent evidence suggests mucin-specific therapeutic approaches could be of benefit because complete MUC5B removal from the airway may be detrimental, whilst the identification of MUC5AC as an essential non-contractile mediator of airway hyperresponsiveness and the role of MUC5AC in tethering mucus plugging suggest that MUC5AC-specific therapies could be of benefit in asthma (Livraghi-Butrico et al., 2017).