EGFR and cancer: In this study, using four types of wt-EGFR-positive cancer cell lines—A549 (lung), DU145 (prostate), PC3 (prostate), and MDA-MB-231 (breast)—we investigated the biochemical nature of the TKI-induced EGFR dimerization, and tested the effects of either chemically disrupting the TKI-induced EGFR dimerization or downregulating total EGFR protein on TKI-resistant cancer cells.