Genetic aberrations causing an exclusive dependence of cancer cells on the EGFR-mediated cell signaling (i.e., oncogenic addiction), which may be found in cancer cells with either wild-type or tyrosine kinase domain-mutated EGFR, are likely the causes or the molecular determinants of the apoptotic responses of cells to EGFR-targeted therapy. The gene discussed is EGFR; the disease is cancer.