DUOX2 and cancer: We evaluated a panel of non-cancer airway epithelial cells and various lung cancer cell lines for mRNA expression of DUOX1 and DUOX2, and observed a general loss of DUOX1 and DUOX2 in most lung cancer cell lines tested (Figure 1a; Supplementary Figure S1A), with the exception of the pulmonary mucoepidermoid cell line H292 and the lung adenocarcinoma cell line Calu-3, two cancer-derived cell lines that maintain many normal airway epithelial features8, 31 and maintain DUOX1 expression.