HAB21 was expressed as either a human IgG1, IgG4, IgG2Δa, or IgG1FcDead subclass and macrophage phagocytosis of DLD-1 tumor cells opsonized with the anti-EGFR antibody cetuximab alone or in combination with hAB21 was quantified by flow cytometry. The gene discussed is EGFR; the disease is neoplasm.