KYNU and astrocytoma (excluding glioblastoma): In view of the functionally relevant intricacies of the Kmo gene [35,53,90] and the recently described presence of functional KMO in astrocytomas [91], it seems especially relevant to assess the localization and function of the third kynurenine-degrading enzyme, kynureninase (Km: ~35 μM; [92]), in parallel with KMO and KATs in these experiments.