NPC1 and nasopharyngeal carcinoma: Earlier studies have shown that BALB/c-Npc1nih mice, which do not express Npc1 protein (Npc1-null) due to a spontaneous mutation in the Npc1 gene, can recapitulate most of the pathological features associated with human NPC disease, with the exception of neurofibrillary tangles [17], [18], [19], [20].