Inhaled corticosteroids (ICS) are also widely used in the treatment of asthma and COPD, but the effects on mucin production observed differ, probably explained by the use of different culture models (cell lines vs. primary cells, patients cells vs. healthy donors) and animal models (Kanoh et al., 2011; Lachowicz-Scroggins et al., 2017; Singanayagam et al., 2018). The gene discussed is MUC5AC; the disease is chronic obstructive pulmonary disease.