SOD1 and neoplasm: In primary cultured spleen cells transfected with Nrf2-siRNA, the WNQP failed to increase in the expression levels of Nrf2, HO-1, HO-2, and SOD-1 (Figures 5E, F) This suggested an important role of Nrf2 in the improvement of immune function during WNQP-mediated inhibition on tumor growth.