EGFR and neoplasm: All isolated tumors from the placebo group expressed high levels of EGFR (Fig. 7B); however, only a weak EGFR staining was examined in mice treated with the monotherapy (Fig. 7C), indicating that the monotherapy is only suitable to kill tumor cells with high EGFR expression, while tumor cells with lower EGFR expression escape from treatment and selectively proliferate.