CP-358,774 (a potent, selective tyrosine kinase inhibitor of human EGFR, produces cell cycle arrest, and initiates apoptosis in human tumor cells overexpressing EGFR) had an antitumor effect in the EGFR-overexpressing human HN5 and human A431 epidermoid carcinomas. Here, EGFR is linked to squamous cell carcinoma.