PDCD1 and colorectal carcinoma: Although exosomal IRF2 induces VEGFC release and the inhibition of IRF2 suppresses SLN metastasis in CRC, IRF2 also inhibits the CXCL3/CXCR2 axis to prevent CRC, and its overexpression reverses CRC cells’ resistance to anti-PD-1 treatment.