Potency index of PZ-39 in sensitizing drug resistance of HEK293/ABCG2 cells.

aMX = mitoxantrone at 0.1 µM which produces ∼10% inhibition of growth (IC10).
bPotency Index = ratio of inhibitor IC50 in the absence and presence of anticancer drug mitoxantrone at low concentration (10).
cPZ-39 has no measurable cytotoxicity within the concentration range used and its IC50 value was estimated to be bigger than that of FTC which is ∼24 µM.