TDO2 and hepatocellular carcinoma: Further Western Blot examining the expression of AhR and its downstream target gene CYP1b1 in LO2 and HCC cell lines showed that cell lines with TDO2 overexpression express relative higher level of AhR and CYP1b1 than the cell line with low expression of TDO2 (Supplementary Figure 1D), providing a clue that TDO2 probably regulated AhR in a translational level, which needs further work to explore.