As shown, CIs for most combinations of CFZ and DOX were far lower than 1.0, indicating synergistic effects on breast cancer cells, and the combination of the lower doses of CFZ and DOX significantly and synergistically induced increasingly cytotoxic effects and apoptosis in breast cancer cells by preventing inhibitory factor κB αlpha (IκBα) degradation in the NF-κB signal pathway and activating JNK apoptosis signaling not p38 MAPK in our assays. Here, MAPK8 is linked to breast cancer.