IDO1 and malignant colon neoplasm: As shown on western blotting in Fig. 1c, IFN-γ treatment significantly elevated the IDO1 protein level in four colon cancer cell lines (HT-29, HCT-116, SW620, DLD-1) and two lung cancer cell lines (H-1299 and A549) and moderately increased IDO1 in CCD-841 and BEAS-2B cells.