Figure 2. Effect of sorafenib on proliferation, apoptosis and cell cycle.

A. Inhibition of cell proliferation. UT-SCC 42A cells were treated with sorafenib as indicated and the cells were counted daily up to 5 d after sorafenib addition. The absolute cell numbers are depicted. B. Enhancement of the anti-proliferative effect of cisplatin. Cells were treated with increasing concentrations of cisplatin with and without 5 μM sorafenib. Three days later, the cell number was quantified, the number of plated cells was subtracted and the numbers were normalized to the untreated control. The fraction of treated cells compared to control (DMSO-treated) cells is depicted. The relative effect of sorafenib alone is given in the inlay. C. Induction of apoptosis. Cells were treated with 10 μM sorafenib and 5 μM cisplatin. Shown is the percentage of apoptotic cells after 72 h treatment as measured by flow cytometry. Cells were incubated with 5 μM staurosporine for 18 h as a positive control. D. Effect on cell cycle distribution. Cells were treated with 10 μM sorafenib and/or 5 μM cisplatin. Cell cycle distributions were determined by flow cytometry for up to 72 h post treatment.