Fig. 4C showed a strong COX-2 immunoreactivity in intestinal polyps, which was markedly decreased by Riccardin D. Quantification of the immunostained cells showed that Riccardin D significantly decreased COX-2 immunoreactivity by 38.9% (p<0.001) in proximal, 55.6% (p<0.001) in middle, 52.6% (p<0.001) in distal, and 44.4% (p<0.001) in polyps of small intestine and colon (Fig. 4C, right). This evidence concerns the gene PTGS2 and intestinal polyp.