TM4SF5 and neoplasm: TM4SF5, as a member of the tetraspan(in), has characteristics for protein-protein binding and intracellular trafficking,50–54 which are important for immune-checkpoint actions.55 TM4SF5 expression in hepatocytes is induced by actions of inflammatory cytokines and chemokines25 and involved in immune escape,28 drug resistance,56,57 tumor metastasis31,32 and angiogenesis,35 via associations with other membrane receptors and/or cytosolic signaling molecules.