EGFR and esophageal squamous cell carcinoma: (A) Six ESCC cell lines were treated with different EGFR blockers (gefitinib, afatinib, osimertinib, cetuximab, and nimotuzumab) at the indicated concentrations (from 0 to 10 μM for TKIs and 0–1000 μg/mL for mAbs).