EGFR and cancer: Explanation to this puzzling phenomenon has been that the wild-type EGFR expressing/overexpressing cancers are not addicted to EGFR function for growth/survival, however, this assertion is challenged by observations that TKIs are potent in inhibiting the growth of wild-type EGFR expressing cells (166–171) and by studies showing wild-type EGFR expressing cells cannot survive after EGFR knockdown by siRNA (142, 145, 172–174).