Given that in vivo overexpression of Tgf-α in mice is clearly pro-oncogenic in the context of wild-type Egfr, leading to pancreatic hyperplasia and mammary epithelial carcinogenesis,19,20 expression of EGF family ligands may be one of the keys to our understanding of tumor sensitivity to EGFR inhibitors. This evidence concerns the gene EGFR and neoplasm.