Fcgr4, also known as CD16-2, is one of the receptors for Fc region of IgG which involve in immune responses. Fcgr4 mainly functions in cellular response to lipopolysaccharide, NK T cell proliferation, regulation of sensory perception of pain, wound healing etc. Three groups are included for Fc γ receptors (FcR), and they are Fc γ RI (CD64), Fc γ RII (CD32), and Fc γ RIII (CD16). Among these, CD64 possess high affinity even for monomeric IgG, while CD32 and CD16 display a relative lower affinity for IgG. Genes encodes these receptors are diverse differing by species and cell types. The aggregation of FcR having immunoreceptor tyrosine-based activation motifs (ITAMs) activates sequentially src family tyrosine kinases and syk family tyrosine kinases that connect transduced signals to common activation pathways shared with other receptors. FcR with ITAMs elicit cell activation, endocytosis, and phagocytosis. Fcgr4 belongs to Fc γ RIII (CD16) group.