GM3 (monosialodihexosylganglioside) is a type of ganglioside. GM3 is the most common membrane-bound glycosphingolipid in tissues, composed of three monosaccharide groups attached to a ceramide backbone. GM3 serves as a precursor for other, more complex gangliosides. GM3 functions as an inhibitor; it inhibits cell growth, the function of growth factor receptors, and generation of cytokines by T cells. N-glycolyl GM3 (NeuGc-GM3) and N-acetyl GM3 (NeuAc-GM3, or simply GM3) are tumor-associated antigens.