PTGS2 and colonic neoplasm: Quercetin of 10.5 mmol/L in a study of the inhibitory potential of 12 flavonoids on the transcriptional capability of Cyclooxygenase-2 (COX-2) gene in DLD-1 human colon cancer cells using a reporter gene assay, was shown to suppress the activity of COX-2 transcription most effectively (Mutoh et al., 2000).