VTCN1 and esophageal squamous cell carcinoma: B7-H4 activates the signal transducer and STAT3 (It can activate cytokines and growth factors, which promotes the transmission of signals from the cell surface to the cell) pathway that promotes the secretion of IL-6, and IL-6 promotes the expression of B7-H4 through binding to the IL-6 receptor, ultimately promoting the development of esophageal squamous cell carcinoma (Chen et al., 2016).