We conclude from this that in human colon cancer cells, endogenous PG production, even when stimulated by IL-1β [28], is too low to affect IL-6 production, and that, conversely, the chemopreventive effect on colon cancer development of COX-2 inhibitors [29] does not involve changes of IL-6 expression. This evidence concerns the gene PTGS2 and colonic neoplasm.