Comprehensive genomic profiling by NGS revealed both cell lines were HER2/HER3/HER4-negative metastatic GC models, while EGFR CN analysis identified GC-1 with high EGFR CN and GC-2 with low CN (Fig. S1A), suggesting a correlation between EGFR status and pan-HER inhibitor sensitivity. The gene discussed is ERBB4; the disease is gastric cancer.