Purpose Niemann-Pick type C (NPC) disease caused by mutations in cholesterol transporters NPC1 or NPC2 is characterized by cholesterol accumulation in late endosomes/lysosomes (LE/Lys). The activation of alternative cholesterol export routes that can bypass NPC1/2 deficiency could provide therapeutic opportunities. We previously demonstrated that gene depletion of the Rab7-GTPase activating protein (GAP) TBC1D15, which hydroly...