TNFRSF4 and neoplasm: Additionally, anti-4-1BB mAb, which bound membrane proximal domains, engaged in more effective complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity killing mechanisms with antibody-dependent cellular phagocytosis less affected.15 Moreover, Zhang et al17 reported that mAb binding to mouse (m)OX40, which blocked ligand binding and bound CRD2, or bound at the membrane proximal domain (CRD4), provide stronger agonistic and anti-tumor activity than mAb binding CRD1 and 3.