The case of breast cancer along with previous data from lung cancers cells demonstrating that Notch 1 might have a role in acquired resistance to gefitinib [23], prompted us to investigate the inhibition of Notch in NSCLC cell lines after cell treatment with γ-secretase inhibitor; N- [N- (3, 5- difluorophenacetyl)- 1- alanyl]- S- phenylglycine t- butyl ester (DAPT), as well as the impact of epidermal growth factor (EGF) in Notch signaling. This evidence concerns the gene EGF and breast carcinoma.