Therefore, we revealed a novel mechanism for BAG2 driving tumor malignancy and chemoresistance through promoting mutant p53 aggregates and counteracting adverse stimuli from chemotherapeutic regimens, which is independent of stabilizing mutant p53 protein, indicating that BAG2 has various effects on mediating p53 GoF and serves as an important factor in rendering chemoresistance in breast cancer. The gene discussed is BAG2; the disease is breast cancer.