Figure 2.

Colony formation assay was carried out to assess the proliferation of HepG2 and HepG2^R single cells treated with sorafenib (HepG2, 1 μM; HepG2^R, 2 μM) and BEZ235 (0.0625 μM) monotherapy or in combination for 24 h. After the drug-containing medium was aspirated and replaced drug-free medium, the cells were further cultured for about 10 days. Cell colonies were fixed with paraformaldehyde and stained with crystal violet solution. The number of colonies in HepG2 and HepG2^R cells after sorafenib mono-treatment was not statistically different from the control number (P>0.05). In contrast, BEZ235 as single agent or in combination with sorafenib, significantly reduced the number of HepG2 and HepG2^R colonies compared with the numbers when treated with sorafenib alone (**P<0.01). Data shown are the mean ± SD from three independent experiments.