NPC2 and nasopharyngeal carcinoma: For example, Niemann-Pick C disease causes intracellular cholesterol accumulation as a result of mutations in the NPC1 or NPC2 gene product that are critical for cholesterol trafficking [Ory, 2004 and HDIs have been shown to largely correct the cholesterol accumulation phenotype both in fibroblasts cultured from human NPC patients (Pipalia et al., 2011) and neural stem cells from NPC−−∕−− mice (Kim et al., 2007).