DDX39A and squamous cell lung carcinoma: The overexpression of DDX39 protein has recently been found in various human tumor tissues and cells, such as lung squamous cell carcinoma (15), gastrointestinal stromal tumors (16, 17), pancreatic cancer (18), prostate cancer (19, 20), hepatocellular carcinoma (9), and malignant mesothelioma (21).