These findings were consistent with independent measurements of the metabolome and transcriptome obtained from the Cancer Cell Line Encyclopedia consortium on ~900 cell lines, where IDO1 expression was associated with kynurenine abundance (P = 8.6 × 10−9) but AFMID expression was not (P = 0.8) (ref. 36) (Extended Data Fig. 5a,b). Here, IDO1 is linked to cancer.