Receptors for the Fc fragment of IgG, or FCGRs, are cell surface glycoproteins of the Ig superfamily (IgSF). These receptors mediate phagocytosis of IgG-coated pathogens and promote activation of effector cells, leading to inflammatory responses and antibody-mediated cellular cytotoxicity. FCRLA may be implicated in B-cell differentiation and lymphomagenesis.