Although amplification and overexpression of epidermal growth factor receptor (EGFR), an RTK sitting upstream of PI3K, was often identified in ESCC and associated with advanced stages and poor prognosis,23 alterations in EGFR failed to differentiate the sensitivity of ESCC cell lines to CYH33 (Fig. 1d). This evidence concerns the gene EGFR and esophageal squamous cell carcinoma.