This was manifested by the concentration-dependent statistical significant elevation in the MDA level, a by-product lipid peroxidation, concurrently with the significant decreases in the activities of the antioxidant CAT and SOD enzymes noticed after 72 h of A-431 cancer cells treatment with Y2O3NPs various concentrations (7.47, 14.98 and 29.89 μg/ml) compared to their values in both the control and doxorubicin-treated A-431 cancer cells (Table 4). The gene discussed is CAT; the disease is cancer.