Hyperactivity of IL-6 through JAK/STAT3 pathway leads to an increase in tumour proliferation, invasiveness, metastatic ability and chemoresistance in colorectal cancer through enhancement of EMT; while actively suppressing antitumour immune response through downregulation of programmed death-ligand 1 (PD-L1)31. The gene discussed is STAT3; the disease is neoplasm.