HGF is a survival factor of EGFR inhibited ErbB2 mammary tumor cells. A.

<p>Western-blot analysis of ErbB2, EGFR and Met expression in mammary tumors obtained from three separate transgenic ErbB2 mutated mice (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044982#s4" target="_blank">materials and methods</a>). Tubulin was used as an internal loading control. <b>B.</b> Phase contrast images of primary cells from ErbB2 mammary tumors (bar = 500 µm). Cells were grown in proliferation medium and either left untreated (Ctrl) or treated with AG1478 (250 nM) or PHA-665752 (250 nM) for 96 h. <b>C.</b> Viable cell count by trypan-blue exclusion staining at 48 h, of immortalized ErbB2 tumor cells treated with the indicated factors (HGF 10 ng/ml (H), IGF-I 100 ng/ml (I), b-FGF 20 ng/ml (F), Neuregulin 20 ng/ml (N); AG1478 250 nM (A)). Untreated control (Ctrl) was set to 100%. Columns, mean (n = 6); bars, S.E.M. *P<0.05. <b>D.</b> Cell cycle distribution examined by propidium iodide staining and FACS analysis of ErbB2 mammary tumor cells cultivated in growth medium and treated with the indicated factors for 16 h (HGF 10 ng/ml, AG1478 250 nM). <b>E.</b> Immortalized ErbB2 tumor cells cultivated in their respective growth medium for 48 h with the indicated factors (HGF 10 ng/ml; AG1478 250 nM; IRESSA 1 µM; TARCEVA 1 µM). Bar = 500 µm.