To quantify membrane protein internalization, we treated the EGFR knockdown model of HNSCC cell lines with either transforming growth factor alpha (TGF-α), a potent ligand that induces EGFR internalization, or with the EGFR tyrosine kinase inhibitor gefitinib as a negative control. The gene discussed is EGFR; the disease is head and neck squamous cell carcinoma.