In contrast to previous results, we found increased expression of biomarker genes for club cells (Secretoglobin Family 1A Member 1, CC10; SCGB1), ciliated cells (Forkhead Box J1; FOXJ1), and pulmonary neuroendocrine cells (tubulin beta 3 class III; TUBB3) in COPD airway epithelium, while no differences were observed for the mucus cell marker MUC5B at the mRNA level (Figure 4B). This evidence concerns the gene SCGB1A1 and chronic obstructive pulmonary disease.