NPC2 and nasopharyngeal carcinoma: Despite evidence that disruption of the functional interaction between the subunits of cis-PTase and NPC2 results in NPC2 mis-localisation to the ER, no study has yet confirmed the presence of other hallmarks of NPC disease cellular pathogenesis in DHDDS or NUS1 cells, namely lysosomal storage of other lipids including GSL and lyso-(bis)phosphatidic acid, endosomal transport-autophagy abnormalities, and lysosomal Ca2+ signalling defects [22,23,24].