EGF and head and neck squamous cell carcinoma: EGFR/EGFR-GFP were immunoprecipitated from lysates of HSC3/EGFR-GFP cells grown in vitro and stimulated with 0–5 ng/ml EGF for 10 min (A–B), lysates of flank (A) and tongue (B) HSC3/EGFR-GFP tumors or lysates of human HNSCC specimens (B).