To assess DNA methylation and expression of SPDEF and FOXA2 during goblet cell differentiation, primary airway epithelial cells, isolated from trachea (non-COPD controls) and bronchial tissue (patients with COPD), were differentiated by culture at the air-liquid interface (ALI) in the presence of cytokine interleukin (IL)-13 to promote goblet cell differentiation. This evidence concerns the gene FOXA2 and chronic obstructive pulmonary disease.