FIGURE 3.

Efflux activity is increased in TCR cells but MDR1 and BCRP expression remain unchanged. (A) Efflux activity was studied by accumulation of rhodamine 123 (Rho 123) using flow cytometry. The efflux activity is increased only in TCR cells compared to parental cells. (B) Efflux activity was studied in the absence or presence of CsA, an inhibitor of MDR1. The addition of CsA reduces the Rho123 efflux percentage in both parental and resistant cell lines. (C) The expression of MDR1 and BCRP detected by flow cytometry indicates that resistant cell lines do not overexpress either ABC transporter