Increased sensitivity to TGF-β-induced apoptosis in oval cells lacking a functional Met receptor. A.

<p>Mouse Met^flx/flx and Met^−/− oval cell lines were serum-starved and incubated in the absence (C) or presence of 1 ng/ml TGF-β (Tβ) for different periods of time. Cells were lysed and caspase-3 activity was measured. Data are mean±SEM of eight independent experiments. <b>B.</b> Cells were treated as in A, detached by tripsinization and incubated with annexin V and PI. Subsequently, fluorescence intensity was measured in a FACScan flow cytometer and the percentage of annexin V positive/PI negative cells was calculated. Data are expressed as fold induction over untreated cells and are mean±SEM of four independent experiments. <b>C.</b> Cells were infected with Ad-CMVCre or Ad-CMVNull for 24 hours, then serum-starved for 4 hours and treated with 1 ng/ml TGF-β for 24 hours. Apoptotic nuclei were visualized and counted after PI staining under a fluorescence microscope. A minimum of 1000 nuclei was counted per condition. <b>D.</b> PCR genotyping of genomic DNA to confirm <i>met</i> deletion in infected cells. <b>Black bars</b>, Met^flx/flx cells. <b>White bars</b>, Met^−/− cells. *<i>P</i><0.05; **<i>P</i><0.01; ***<i>P</i><0.001 (treated versus untreated); #<i>P</i><0.05 (treated Met^−/− versus treated Met^flx/flx).