Tunicamycin-induced cytotoxicity is enhanced in combination with other therapy. Cytotoxicity was measured using the MTT assay. All data represent mean plus or minus SD of triplicate experiments. (A,C) BCWM.1 cells were cultured with tunicamycin (0.01 μg/mL and 0.1 μg/mL) in the absence and presence of bortezomib (5 nM and 10 nM; A) and fludarabine (5 μg/mL and 10 μg/mL; C). (B,D) Normalized isobologram produced by the software Calcusyn. Values below the threshold line represent synergistic combination. Table shows affected fractions (Fa) and combination indexes (CI) with tunicamycin and other therapy. Numbers (#) correspond to those provided in the normalized isobologram. (B) BCWM.1 cells were cultured with either tunicamycin, bortezomib, or the combination for 48 hours. (D) BCWM.1 cells were cultured with tunicamycin, fludarabine, and the combination for 48 hours.