NPC1L1 and cancer: Notably, we found chemotherapy agents/verapamil treatment further induced cell death of MDR cancer cells that were cultured in serum‐free medium where cholesterol and vitamin E were not present, compared with normal culture conditions (Fig 3J–K), suggesting that MDR cancer cells survive treatment with chemotherapy agents/verapamil due to absorption of vitamin E from serum by activating NPC1L1.