reported that the DCs recruited by the carcinoma-associated fibroblasts (CAFs) in hepatocellular carcinoma (HCC) get converted to IDO producing regulatory DCs which exhibits an increased ability to suppress T cell proliferation, and upregulation of Tregs through IL-6 mediated Signal transducer and activator of transcription 3 (STAT3) activation (37). Here, IDO1 is linked to hepatocellular carcinoma.