To circumvent this limitation, we made use of a previously established NPC1−/− ARPE-19 cell line—which, unlike skin fibroblasts, recapitulate several features of the pathological cellular phenotype of NPC—and transduced it with retroviral particles loaded with different constructs encoding different WT and mutant variants of NPC1. This evidence concerns the gene NPC1 and nasopharyngeal carcinoma.