The proto-oncogene c-MYC activates the kynurenine pathway in CRC cells by promoting the transcription of the tryptophan importers SLC1A5 and SLC7A5 and the tryptophan metabolizing enzyme arylformamidase AFMID (Venkateswaran et al., 2019). Here, AFMID is linked to colorectal carcinoma.