IDO1 and hepatocellular carcinoma: In cellular models of hepatocellular carcinoma (HCC) with an inducible knockdown (in HuH-7 and Sk-Hep1 cells), it has been shown that the enhancement of AhR and β-catenin pathways is coordinated and is a consequence of the activation of an enzyme called IDO1, which catalyzes the formation of the tryptophan metabolite Kyn.