To examine the function of EI24 in ESCC, first, we examined the protein expression of EI24 endogenously in five tumor-derived ESCC cell lines (EC9706, KYSE150, TE-1, EC109, and Eca109) by Western blotting and found that EC9706 and EC109 cells had lower levels of EI24 protein relative to the other cells, while KYSE150 and TE-1 cells expressed EI24 at a much higher level (Supplementary Figure S1A). Here, EI24 is linked to esophageal squamous cell carcinoma.