SP4 and malignant colon neoplasm: Both curcumin and the potent RL197 analog induced ROS (Figure5A) and decreased expression of Sp1, Sp3, Sp4 and Sp-regulated proteins (Figures2 and3) in colon cancer cells, and cotreatment with GSH inhibited these responses and also partially reversed the growth inhibitory effects of these compounds (Figure5D).