Finally, the AhR has been also shown to be associated with Src-mediated epidermal growth factor-induced stimulation of colon cancer cell proliferation, as well as with sustainability of indoleamine-2,3-dioxygenase expression and activity, which catalyzes the first step in the kynurenine pathway (that in turn leads to formation of endogenous AhR ligands), which also contributes to tumorigenesis [29,30]. This evidence concerns the gene AHR and malignant colon neoplasm.