However, Bit1 level was differentially expressed in these ESCC cell lines, and relative high level was displayed in EC9706, Eca109, TE13 and KYSE-70 cells, the other ESCC cell lines harbored lower Bit1 level, the difference was statistical significance (P < 0.05) (Fig. 1a and b). This evidence concerns the gene PTRH2 and esophageal squamous cell carcinoma.