IRX1 and non-small cell lung carcinoma: We analyzed the promoter methylation of the IRX1 promoter region of five NSCLC cell lines (A549, A427, HCC15, H322, and H358) and 11 SCLC cell lines (HTB171, HTB175, SCLC21H, SCLC22H, SCLC24H, H82, HTB187, H209, H510, H1092, and H1184) by combined bisulfite restriction analysis (Figure 1c,d).