fourth glycosphingolipid of the five lipid haptens that have been isolated from animal cells; isolated from rat lymphosarcoma as specific antigen to transplanted rat tumors; structure determined to be N-acetylgalactosaminyl (beta 1 to 3)galactosyl(alpha 1 to 3)galactosyl (beta 1 to 4)glucosylceramide; from rat colon and rat adenocarcinoma