KMO and cancer: KMO is a pivotal enzyme in the kynurenine‐mediated tryptophan degradation pathway; it positively regulates proliferation, migration, and invasion of tumor cells, and may serve as a novel prognostic marker in various cancers.29, 30 Recently, investigators revealed the crystal structure of Saccharomyces cerevisiae KMO, in the free form and in complex with the tight‐binding inhibitor UPF 648,31 which will promote the search for new KMO inhibitors in targeted therapies against neurodegenerative diseases and tumor.