 The EGF epidermal growth factor system with its 4 receptor EGFR, HER2, HER3 and HER4 and related proteins are known to play an active role in the development of cancer. In non-small cell lung cancer NSCLC especially EGFR has been studied. Inhibition of EGFR is associated with prolonged survival especially in patients with mutations in the EGFR EGFR M 10-15 of the patients with NSCLC harbor a mutation in the tumors EGFR. This receptor is the target for treatment with the tyrosine kinase inhibitor TKI erlotinib. The response rate for erlotinib treatment in EGFR M NSCLC is around 75 as opposed to response rates around 30 for treatment with traditional chemotherapy. 