Emergence of gefitinib-resistant cell line with a similar but modest EMT-like phenotype such as vimentin expression without obvious fibroblastic morphology after repetitive gefitinib treatment was also observed in another HNSCC line, HSC3 (Supplementary Figure 1S), but not in HSC2 and UMSCC6 cell lines. The gene discussed is VIM; the disease is head and neck squamous cell carcinoma.