Fig. 2

P-glycoprotein expression in hCMEC/D3 and RBE4 wildtype and MDR1-EGFP transduced cells. Representative western blots (30 µg protein/sample) (A, C) and quantification (B, D) of Pgp expression in the different cell lines. In both hCMEC/D3- and RBE4-MDR1-EGFP cells, the addition of doxycycline (dox) leads to the induction of Pgp expression. In comparison to wild-type (WT) cells, Pgp expression in RBE4- and hCMEC/D3-MDR1-EGFP cells in the presence of dox was increased by 9- and sevenfold, respectively. Dox did not affect Pgp expression in WT cells. Data are presented as means + SEM; sample size (biological replicates) is shown below the bars. Asterisks indicate significant differences between cell types as calculated by one-way ANOVA followed by Dunnett’s multiple comparisons test (P < 0.0001)