In general, each stage of carcinogen-induced colon tumorigenesis involves several functional pathways, for instance, Apc/β-catenin, Kras, c-Myc and global hypermethylation are activated in the early stage, while COX2 and iNOS are activated in the progression from adenoma to carcinoma [25] (Figure 2A). Here, KRAS is linked to carcinoma.