MSK-Leuk1 and KYSE450 cells were treated with the indicated concentrations of 17-AAG, celastrol or gedunin for 2 h. Subsequently, cells received vehicle or TS for 5 h, and were then harvested for Western blot analysis. Cellular lysate protein (100 μg/lane) was loaded onto a 10% SDS–polyacrylamide gel, electrophoresed and subsequently transferred onto nitrocellulose. Immunoblots were probed with antibodies specific for CYP1A1 (panel A), CYP1B1 (panel B) and β-actin.