Transport of [3H]LTC4 in the presence of ATP. Uptake of [3H]LTC4 into MRP1 ‘inside-out’ vesicles was measured in the presence of [3H]LTC4 alone (□), 25 μM GSH (■), 25 μM PABA/NO (●), or 25 μM GSH and 25 μM PABA/NO (엯) (A) or 500 nM GSH and 1 μg GSTπ (■), 50 μM PABA/NO and 1 μg GSTπ (●), 50 μM PABA/NO and 500 nM GSH (□), or 500 nM GSH, 50 μM PABA/NO, and 1 μg GSTπ (엯) (B), as detailed under Materials and Methods. Data are represented as means ± S.D. of three independent experiments.