BRAF and colonic neoplasm: As this seemed an interesting example of a synergistic interaction that only takes place in a particular cancer cell type (i. e. BRAF-mutant, EGFR overexpressing colon cancer cell lines), we performed curve shift assays with the EGFR inhibitor gefitinib and the BRAF inhibitors vemurafenib and dabrafenib, in proliferation assays with the BRAF-mutant colon carcinoma WiDr cell line (Fig 4).