Also, smoking history (pack-years) in smokers with normal lung function and smokers with COPD, as well as in ex-smokers with COPD, correlated positively with MUC5AC expression in goblet cells (Figure 3C) and negatively with the immunohistochemical MUC5B expression in goblet cells (Figure 3D). The gene discussed is MUC5AC; the disease is chronic obstructive pulmonary disease.