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. 2005 Feb 24;102(10):3788–3793. doi: 10.1073/pnas.0409773102

Fig. 2.

Fig. 2.

PI3K regulatory subunit p85 binds ErbB-3 in a gefitinib-dependent manner exclusively in NSCLC cell lines sensitive to gefitinib. (A) Three NSCLC cell lines resistant to gefitinib (H23, A549, and H1299) and three cell lines sensitive to gefitinib (H358, Calu-3, and A431) were grown in the presence or absence of gefitinib (1 μM) for 6 h. Extracts (≈1 mg) were immunoprecipitated with an anti-p85 antibody and subjected to immunoblot assay with anti-PTyr, anti-p85, and anti-ErbB-3 antibodies. * marks a PTyr protein observed in p85 coprecipitations in gefitinib-sensitive cells whose association is significantly diminished in the presence of gefitinib. (B) 50 micrograms of extracts from the cell lines shown were probed with antibodies against ErbB-3, EGFR, ErbB-2, PTEN, and β-actin. * denotes cells that have an IC50 of <1 μM to gefitinib (gefitinib-sensitive). Note that H322 and H522 cells are resistant to 1 μM gefitinib (data not shown).