and a reversed process MET is suggested to occur endowing a less motile phenotype. Accordingly, we further investigated whether arresten overexpression could restore the epithelial characteristics of the tumor cells. The 2-Pyrrolidinecarboxamide, N-[(2S)-2-hydroxy-2-phenylethyl]-4-(methoxyimino)-1-[(2′-methyl[1,1′-biphenyl]-4-yl)carbonyl]-, (2S,4E)- Arr-HSC cells growing in tightly packed clusters expressed more epithelial marker E-cadherin on their cell surfaces than the Ctrl-HSC cells, which is likely to contribute to their epithelial-like morphology and reduced motility. Besides the recruitment of E-cadherin to the Arr-HSC cell membrane, its expression in these cells was increased when compared to the Ctrl-HSC cells. The amount of E-cadherin mRNA in the Arr-HSC cells of protein both significantly higher than in control cells. Strong immunofluorescence signals for the mesenchymal marker vimentin were observed in some individual Ctrl-HSC and Arr-HSC cells, but evident differences in these signals could not be detected between the cell lines. We next wished to determine the reason underlying the thin top cell layer formed by the Arr-HSC cells in the organotypic model, and set out to study tumor cell proliferation and apoptosis. The number of proliferating Ki-67-positive tumor cells was smaller, but not statistically significant, in the Arr-HSC than in the Ctrl-HSC 3D cultures, which is in agreement with our observation on reduced tumor cell proliferation in Arr-HSC xenografts. The TUNEL assay showed that the Arr-HSC cells underwent apoptosis more often than the control cells in the 3D model. Since the TUNEL assay also detects other types of cell death in addition to apoptosis, we wanted to confirm our finding by caspase-3 staining. We observed a similar and significant trend on increased apoptosis in Arr-HSC cells although the 859212-16-1 distributor increase was milder than the one in the TUNEL assay. In HSC-3 xenografts, however, only few TUNEL-positive cells were detected mainly in the keratinized central tumor areas. We have previously shown that recombinant arresten affects mitochondrial apoptosisrelated Bcl-family signaling molecules in microvascular endothelial cells. In the current experiment the pro-apoptotic Bax protein showed increase in the Arr-HSC cells relative to the Ctrl-HSC cells, whereas the anti-apoptotic Bcl-xL protein level concomitantly showed a decreased, although not statistically significant, trend of the controls, thus shifting the balance towards a situation favoring apoptosis. To pursue the mechanisms underlying the altered behavior and morphology of Arr-HSC cells we performed measurements using electric cell-substrate impedance sensing, a method that provides quantitative data on cell attachment, spreading and the strength of cell-cell contacts by monitoring changes in the system impedance.