GPNMB and nasopharyngeal carcinoma: They also found that miglustat (N-butyl-1-deoxynojirimycin), a glucosylceramide synthase and an approved drug for NPC patients in Europe and Japan, reduced Gpnmb mRNA expression induced by U18666A in the RAW 264.7 murine macrophage cell line, probably through the inhibition of glucosylceramide synthase but not cholesterol synthesis.