The effect of vardenafil and tadalafil on the reversal of ABCB1-mediated resistance to colchicine, paclitaxel and cisplatin in drug selected cell line.

Cell survival was determined by MTT assay as described in “Materials and Methods”. Data are expressed as the means ± SD of at least three independent experiments performed in triplicate. The magnitude of the fold-reversal of MDR fold reversal (values given in parentheses) was calculated by dividing the IC50 for cells with the anticancer drug in the absence of inhibitor by that obtained in the presence of inhibitor.
**represents P<0.01, for values versus that obtained in the absence of inhibitor.