IDO1 and hepatocellular carcinoma: CXCR2 up‐regulated by IL‐8 or IFN‐β promote neutrophils recruitment.30, 31 CXCL5 promote intra‐tumoral neutrophil infiltration through PI3K‐Akt and ERK1/2 signaling pathways.32 However, no direct evidence shows IDO can promote neutrophils recruitment in HCC.