TUG1 and esophageal squamous cell carcinoma: To further confirm the expression level of TUG1 in ESCC cells, qRT-PCR analysis was performed in ESCC parental cell lines (ECA109 and EC9706), DDP-resistant cell lines (ECA109/DDP and EC9706/DDP) and normal immortalized esophageal epithelial cell line HET-1A.