Mellinghoff et al. [2], however, identified two molecular events in tumor patients who could be related with a positive response to erlotinib or gefitinib: the expression of EGFRvIII, and PTEN, a tumor-suppressor protein that inhibits the phosphatidylinositol 3′ kinase signaling pathway downstream EGFR. This evidence concerns the gene PTEN and neoplasm.