Viability was assessed with MTT assay in HCC cells at 48 h after treatment with free DOX, MetFab-DOX and MetFab, respectively. In the experiment, the equivalent doxorubicin concentrations in the free DOX and MetFab-DOX were 10, 7.5, 5, 2.5, 1, 0.5 or 0.25 µg/mL, while the MetFab had an equivalent antibody concentration as MetFab-DOX, which was 22.86, 17.14, 11.43, 5.71, 2.29, 1.14, 0.57 µg/mL. In all those cell lines screened, no visible cytotoxicity was found in cells treated with MetFab only. There were significant differences in survival rate of HCC cells between MetFab group and MetFab-DOX group (P<0.05) or DOX group (P<0.05). Furthermore, there were significant differences in the survival rate of HCC cells between MetFab group and MetFab-DOX group (P<0.05). However, in NIH3T3 cells, there were significant differences between DOX group and MetFab group (P<0.05). In contrast, there was no significant difference between MetFab-DOX group and MetFab group (P>0.05). Results were confirmed with duplicate experiments. The survival rates of treated samples were normalized to the untreated controls.