GLTP and nasopharyngeal carcinoma: In this study, three sphingolipid-related proteins are downregulated in NPC mice: Cers2, a ceramide synthase [41]; Ugt8, a key enzyme in synthesizing the most abundant myelin lipid - galactosylceramide (GalCer); and Gltp, a transfer protein for various glycosphingolipids between membranes.