ABCB1 and cancer: Nobiletin at achievable nontoxic plasma concentrations (0.5 to 9 μM)26 significantly sensitizes the ABCB1 overexpressing MDR cancer cell lines by modulating the ABCB1 function and inhibiting the AKT/ERK/Nrf2 pathways, therefore, has the potential to be used in combination therapies to treat MDR.