EGFR and non-small cell lung carcinoma: In addition to increasing the levels of EGFR, AXL, HER2, and HER3, upregulation of cytoplasmic EGFR and reduced membranous EGFR (Figure 4b and Table 2) may contribute to reducing the efficacy of gefitinib in patients with LDOC1(−) EGFRM NSCLC, given that the cytoplasmic location of EGFR can hinder drug targeting.