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. 2011 Apr 12;286(23):20558–20568. doi: 10.1074/jbc.M111.240796

FIGURE 6.

FIGURE 6.

Nuclear EGFR enhances transcriptional activation of BCRP/ABCG2 in A431/GR cells via recruitment to the BCRP/ABCG2 promoter. A, the DNA binding consensus sites of EGFR in BCRP/ABCG2 promoter are shown. B, three probes for DNA affinity precipitation assay were designed according to the sequence of human BCRP/ABCG2 promoter. C, the binding of EGFR to BCRP/ABCG2 promoter was analyzed by DNA affinity precipitation assay (left). The inputs of probes were shown in at the right. D, the binding of EGFR to BCRP/ABCG2 promoter was analyzed by chromatin immunoprecipitation (ChIP). E, transcriptional activities of BCRP/ABCG2 in A431 and A431/GR cells were analyzed by luciferase reporter assay. F, effects of EGFR Ser-229 mutations on EGFR-induced BCRP/ABCG2 promoter activity were analyzed in A431/GR cell by luciferase reporter assay. Error bars in E and F denote S.E. (n = 3). G, protein expression of BCRP/ABCG2 in HEK293 cells co-transfected with EGFR Ser-229 mutants. H, the proposed model for the mechanism underlying nuclear EGFR-mediated BCRP/ABCG2 expression conferring gefitinib resistance.