In this study, we found that ERV3-2 expression was correlated with IDO-1 expression in most (10/11) of these cancer types (Figure 4D), IDO-2 expression in all (11/11) of these cancer types (Figure 4E), and TDO-2 expression in only a few (4/11) of these cancer types (Figure 4F). This evidence concerns the gene TDO2 and cancer.