CAT and neoplasm: To achieve the ultimate goal of this research, we investigated the levels of lipid peroxidation and activities of antioxidant defense enzymes superoxide dismutase (SOD) and catalase (CAT) in liver homogenates of tumor bearing mice treated by the antitumor drugs doxorubicin, bleomycin, or after total body irradiation alone and compared to the levels of the same parameters measured after pretreatment with SLENU.