Fig. 1

Doxorubicin synergized with bortezomib to induce cell death in U266B1 cells. U266B1 cells were treated with either no compound, 6.25 nM Bortezomib, or one of the following compounds: 12.5 μg/ml Gemcitabine (A), 10 μM Alisertib (B), 10 μM Regorafenib (C), 20 μM EPZ015666 (D), 10 μM Lenalidomide (E), 10 μM Pomalidomide (F), 10 μM Dexamethasone (G), 1 μM Doxorubicin (H), or a combination of bortezomib with one of the listed compounds. After 24 h, trypan blue exclusion assays were conducted to assess cell death. At these concentrations, bortezomib induced 30–40% cell death, whereas each tested compound resulted in 10–20% cell death. The experimental death value (E) represents the observed cell death resulting from the combination treatment, whereas the theoretical additive value (T) represents the sum of cell death induced by each drug individually. Statistical significance was determined using one-way ANOVA followed by Tukey’s multiple comparison test, with p-values of < 0.05 (*), < 0.01 (**), < 0.001 (***), and < 0.0001 (****); ns indicates no significance. All experiments were performed independently three times