Moreover, in adenomatous polyposis coli (APC), a key tumor suppressor gene, deficient CRC, tryptophan 2,3-dioxygenase 2 (TDO2) was identified as an essential effector that, via Kyn-AhR pathway, upregulate glycolysis and anabolic cancer cell growth [36]. This evidence concerns the gene TDO2 and colorectal carcinoma.