GPR39 and esophageal squamous cell carcinoma: The correlation between the GPR39 overexpression and clinicopathologic features of ESCC including age (≤60 versus >60), gender (male versus female), tumor invasion (T stage: tumor depth; T3, T4 versus T1, T2), lymph nodes metastasis (N stage; N0 versus N1), TNM stage (I, IIa versus IIb, III-IV), was studied (Table 1).