MUC5AC and chronic obstructive pulmonary disease: There was a reduction in the proportion of ciliated cells (β-tubulin) (23 ± 2.2 vs. 28.1 ± 3.3, P < 0.05), and an increase in club cells (CC10) (23 ± 1.6 vs. 16.2 ± 1.4, P < 0.001) and goblet cells (MUC5AC) (25.4 ± 1.8 vs. 20.6 ± 2.0, P < 0.01) in COPD cultures compared to healthy control cultures (Figure 1B).