It should be noted that many of these genes were expressed at high levels within the normal mucosa, in particular, MMP-9, PLA2G6 and ptgs2. A recent study by Chen et al (2004) has also shown high mRNA expression levels of several inflammation-related genes in normal-appearing colon mucosa of patients with colon cancer. This evidence concerns the gene PTGS2 and malignant colon neoplasm.