Figure 2. Mebendazole (MBZ) effectively inhibits the cell viability and proliferation of human CR ovarian cancer lines. (A and B) Crystal violet cell viability assay. Subconfluent OVCAR8 and OVCAR8CR (A) and SKOV3 and SKOV3CR (B) were treated with the indicated concentrations of MBZ. At 72 h post treatment, cells were fixed and subjected to crystal violet staining (a). Representative results are shown. The stained cells were dissolved and measured quantitatively for optical absorbance (b). **p < 0.01, compared with that of the respective cells treated with 0 μM MBZ (or DMSO solvent control) group. (C) WST-1 cell proliferation assay. Subconfluent OVCAR8CR (a) and SKOV3CR (b) cells were seeded in 96-well plates and treated with MBZ at the indicated concentrations. At 72 h after treatment, the WST-1 regent (Takara BIO USA, Inc.) was added to each well, and incubated for 2 h prior to the absorbance reading of each well. The IC50 values were calculated by using the AAT Bioquest online tools. All assay conditions were done in triplicate.