Another enzyme withan immunosuppressive function is L-amino acid oxidase (IL4I1), which mediatesthe synthesis of the tryptophan metabolites that activate AhR, similar to IDO1.This leads to immunosuppression and tumor progression in murine models,although further research is needed to confirm whether IL4I1 is activelyutilized by immune cells per se [63]. This evidence concerns the gene IL4I1 and neoplasm.