STAT3 and esophageal squamous cell carcinoma: In order to further investigate the role of STAT3 in ESCC, two ESCC cell lines Eca109 and Kyse30 were treated with different concentrations of Stattic (0, 0.5, 1, 2, 4, 8, 10, and 20 μM) to inhibit the activation of STAT3.