To investigate the potential mechanisms of Nimotuzumab on promoting radiosensitivity of ESCC cells with high-level of EGFR, we first examined expression levels of EGFR and phosphorylated EGFR (i.e., p-EGFR, an active EGFR) before and after the administration of Nimotuzumab in ESCC cells. Here, EGFR is linked to esophageal squamous cell carcinoma.