Ganglioside G is a glycosphingolipid component of cellular membranes, primarily the plasma membrane. Gangliosides isolated from apoptogenic glioblastoma multiforme (GBM) cells are enriched in ganglioside G compared with nonapoptogenic GBM cells, and ganglioside G induces activated T cell death when used at a concentration of 150 μg/ml in vitro. Serum ganglioside G levels are increased in patients with breast cancer or cholangiocarcinoma. Levels of ganglioside G are elevated in the brain of patients with Sandhoff disease, as well as feline and mouse models of the disease. Ganglioside G accumulates in the lysosomes of individuals with Tay-Sachs disease and G-activator deficiency, as well as in the CNS of patients with and animal models of mucopolysaccharide storage disorders and Niemann-Pick disease types A, C1, and C2. Ganglioside G mixture contains ganglioside G molecular species with C18:1 and C20:1 sphingoid backbones.