MAPK1 and esophageal squamous cell carcinoma: To investigate the role of EGFR-related pathway activities in ESCC progression, we used tissue microarray (TMA) technology and immunohistochemical (IHC) analysis to evaluate the activities of EGFR and its downstream effectors AKT, ERK, and STAT3 in ESCC; we also analyzed the relationships of these markers and their association with prognosis in ESCC patients.