However, the mass spectrometric analyses, coupled with other assays, confirmed that MUC5AC to MUC5B ratios were increased (~1.2) at baseline in patients with COPD compared with healthy controls (~0.2) and remained at similar ratios during exacerbations, consistent with coordinate upregulation of MUC5AC and MUC5B in individuals with resting or exacerbating COPD. The gene discussed is MUC5AC; the disease is chronic obstructive pulmonary disease.