To investigate whether relative levels of Mig6 and EGFR expression correlate with the clinical drug response to anti-EGFR TKIs, we examined Mig6 and EGFR expression immunohistochemically and in blinded fashion on tissues from a cohort of lung cancer patients who had previously been treated prospectively with gefitinib alone (Figure 6A). This evidence concerns the gene ERRFI1 and lung carcinoma.