The extract of Eca-109 cells, which presented the highest CDC25B protein level among the ESCC tumor cell lines tested (Eca-109, Kyse140, TE-1 and the immortalized cell line NE-3) (Figure 1A), was used as the source of CDC25B antigen for reverse capture ELISAs. This evidence concerns the gene CDC25B and esophageal squamous cell carcinoma.