Fig. 5.

Cell viability assays. Vector-transfected KB-3 cells or cells transiently transfected for 24 h with UGT1A10, UGT2B4, or pcDNA3.1 vector were treated with the indicated concentrations of C-1305 (A) or C-1311 (B) for 72 hours and subjected to MTT cell viability assay as described under Methods and Materials. Cell viability is expressed relative to cells exposed to vehicle. The curves shown are representative of eight independent experiments for C-1305 and five independent experiments for C-1311 (see Table 1).