Celastrol improves the efficacy of chemotherapeutic drugs in CRC. (A) HT29 cells were treated with 2 μM celastrol and 2.5 μM 5-FU or the combination for 24 h, and cell proliferation was analyzed by MTS assay. (B) HT29 cells were treated with 2 μM celastrol and 1 μM salinomycin or the combination for 24 h, and cell proliferation was analyzed by MTS assay. (C) HT29 cells were treated with 2 μM celastrol and 2 mM 1400W or the combination for 24 h, and cell proliferation was analyzed by MTS assay. (D) HT29 cells were treated with 2 μM celastrol and 2 mM L-NIO or the combination for 24 h, and cell proliferation was analyzed by MTS assay. All data are shown as the mean ± SEM. *p<.05, **p<.01, ***p<.001 vs. control group. CEL = celastrol. Sal = Salinomycin.