Addition to the immunomodulatory effects of IDO1 on tumour cells, we speculated that IDC cells (via IFNγ) -induced IDO1 in ECs could catalyse the oxidation of L-tryptophan into kynurenine, which results in a reduction in the availability of tryptophan for the TSP1 synthesis by ECs. This evidence concerns the gene IDO1 and neoplasm.