Some bacteria increase COX-2 expression in macrophages infected with colon cancer E. coli compared with macrophages infected with commensal indicating that tumor- infiltrating bacteria have the ability to enhance the expression of COX-2 that, in turn, will enable the tumor cells and tumor infiltrating macrophages to enhance their PGE2, a immunosuppressor [84]. This evidence concerns the gene PTGS2 and malignant colon neoplasm.