Fig. 4.

Bortezomib is able to reduce the expression and function of P-glycoprotein. When RPMI-Dox40 (a) and DLKP-A (b) cells were treated with 4 and 16 nM bortezomib, respectively, immunoblot analysis demonstrated a reduction in the level of P-gp expression by 24 h. These images were representative of three experiments. GAPDH was employed as a loading control. Bortezomib treatment inhibited rhodamine-123 efflux in RPMI-Dox40 cells with maximum inhibition at 120 min for all doses tested (c). The experiment was performed in triplicate, and results were expressed relative to control at each time point (mean of the median intensity of rhodamine-123 fluorescence ± SEM)