Figure 1.

Analysis of c-Met phosphorylation and HGF concentration in lungs of Kras^LA1 mice. A, Tyr-1234/1235-phosphorylation of c-Met in whole-lung lysates was higher in Kras^LA1 mice than in wild-type (WT) littermates. Western blot analysis of Tyr1234-phosphorylated c-met (P-met) and total c-met performed on whole-lung lysates from Kras^LA1 (n = 3) and wild-type (n = 3) littermates. B, comparison of HGF concentrations in bronchoalveolar lavage samples reveals higher levels in Kras^LA1 mice (n =9) than in wild-type (WT) littermates (n =6). HGF concentrations were measured by ELISA (mean value ± S.E.M). C, c-Met was expressed in multiple cell types within premalignant lung lesions of Kras^LA1 mice. Representative immunohistochemical stains for c-met in two lung adenomas (panels a-d). One adenoma illustrated at 4× (panel a) and 40× (panel b) magnifications to show the predominantly cytoplasmic staining, and the other adenoma stained in the presence (panel c) or absence (panel d) of primary antibody to demonstrate the specificity of staining (both illustrated at ×4 magnification). Dual-immunofluoresence staining was performed using antibodies against total c-met (panels g, l, and q) and markers for specific cell types, including surfactant protein-C (SPC) for tumor cells (panel h), F4/80 for macrophages (panel m), and CD31 for vascular endothelial cells (panel r). c-Met stains were merged with corresponding stains for SPC (panel i), F4/80 (panel n), and CD31 (panel s). Light microscopic fields (panels e, j, and o) and DAPI stains (panels f, k, and p) are illustrated. Panels e-s are ×10 magnification.