To explore whether the elevated DJ-1 in serum was secreted by ESCC cells, we examined the DJ-1 levels by ELISA in the cell supernatants of six ESCC cell lines (KYSE-30, KYSE-150, KYSE-450, ECA-109, TE-1 and TE-10) after irradiation. This evidence concerns the gene PARK7 and esophageal squamous cell carcinoma.