SOX2 and esophageal squamous cell carcinoma: (1) The serum levels and positivity rates of five antibodies (PGP9.5, SOX2, GBU4-5, MAGE-A1, and CAGE) were higher in the ESCC group than in the control group (P < 0.05) and the positive expression rate of the combined serum 7-TAAB in the ESCC group was significantly higher than that in the control group (P < 0.05).