Meng et al. (2019) found that knockdown of CIT inhibited aggressiveness and tumorigenesis of breast cancer cells. Moreover, Sahin et al. (2019) confirmed that CIT is enhanced in multiple myeloma, and silencing of CIT inhibited the growth of multiple myeloma in vivo and in vitro. In this study, CIT was highly expressed in both ESCC tissues and cell lines. Knockdown of CIT markedly inhibited proliferation and promoted cell apoptosis in Eca-109 cells in vitro. Moreover, in vivo experiments also confirmed that knocking down CIT inhibited tumorigenicity of Eca-109 cells. This evidence concerns the gene CIT and esophageal squamous cell carcinoma.