Since PPARY is expressed by many tissues,albeit at a low level,we must await the verdict off time for any unforeseen effects of long-term stimulation with thiazolidinediones For example,PPARY activation in macrophages can re duce the production of some inflammatory cytocytes to macrophages in the vascular wall. stimulation of PPARY in colon cells has been variously reported to incrase and decrease division and differentiation of these cell in different animals and cell models;thus,familial polyposis coli is a contraindication to thiazolidinediones on theoretical grounds.