*4.2. Transient Expression of ABCB1*

HEK293T cells were grown in DMEM high glucose (ThermoFisher Sci, Waltham, MA, USA) supplemented with 10% fetal bovine serum (FBS; ThermoFisher Sci, Waltham, MA, USA) at 37 ◦C in a humidified incubator with 5% CO2. For transient transfection 1.2 × 10<sup>6</sup> cells were seeded onto a T25 culture flask. Twenty-four hours post seeding the cells were transfected with 10 µg plasmid DNA in complex with 15 µg linear polyethylenimine (Sigma-Aldrich, St. Louis, MO, USA). Cells were cultured for a further 48 h before harvesting with TrypLE (ThermoFisher Sci, Waltham, MA, USA) and quenching of the trypsin with culture medium.
