SPDEF and chronic obstructive pulmonary disease: COPD-derived cells presented significant lower methylation levels of CpG site number 6 in the SPDEF promoter (85% in control, 73% in COPD, Fig. 5a) and also lower methylation levels of three CpG sites in the FOXA2 promoter (CpG number 10: 4% in control and 2% in COPD, CpG number 11: 5% in control and 3% in COPD, CpG number 15: 13% in control and 9% in COPD, Fig. 5b) than control-derived cells at ALI day 14.