Alpha-Galactosylceramide (α-GalCer, KRN7000) is a synthetic glycolipid derived from structure-activity relationship studies of galactosylceramides isolated from the marine sponge Agelas mauritianus. α-GalCer is a strong immunostimulant and shows potent anti-tumour activity in many in vivo models. α-GalCer is a potent activator of iNKT cells, and a model CD1d antigen. The invariant T cell receptor of the iNKT cell is able to bind the CD1d:glycolipid complex leading to iNKT cell in both mice and humans.