GPNMB and nasopharyngeal carcinoma: The driver of Gpnmb expression in RAW264.7 cells is most likely a GSL, as incubation with the GCS inhibitor N-butyl-1-deoxynojirimycin (NB-DNJ, Zavesca), the only EMA-approved drug for the treatment of NPC, lowered GSLs such as GlcCer and LacCer and concomitantly Gpnmb, while not lowering cholesterol levels.