The downregulation of DENND2D has been observed not only in NSCLC cell lines and lung squamous cell carcinoma (SCC) tissues but also in immortalized human bronchial epithelial (IHBE) cell lines and precancerous lesions, indicating that the downregulation of DENND2D may be an early event in lung cancer10. This evidence concerns the gene DENND2D and squamous cell lung carcinoma.