TDO2 and cancer: We computed Spearman’s rank correlations between the expression of IMPACT, tryptophan dioxygenase genes (IDO1, IDO2, TDO2), and representative genes on the stress response GCN2 pathway (EIF2AK4 (GCN2), EIF2S1, DDIT3 (CHOP), ATF4), as well as the amino acid sensing mTOR pathway (MTOR, RPS6KB1) for all the 52 normal and cancer tissue types examined (Fig. 2).