Moreover, as shown in Figures S4B and S4C, we observed a significant decrease in mRNA levels of basal epithelial cell markers (Tumor Protein P63 (TP63), Keratin-5 (KRT5) and Keratin-14 (KRT14)) as well as a profound increased expression of club cell secretory marker (Secretoglobin Familiy 1A Member 1 (SCGB1A1)), ciliogenesis marker (Forkhead Box J1 (FOXJ1)) and goblet cell differentiation marker (Mucin 5AC, Oligomeric Mucus/Gel-Forming (MUC5AC)) at day 28 compared to day 0 of differentiation in both non-COPD patients and COPD patients. This evidence concerns the gene KRT5 and chronic obstructive pulmonary disease.