Figure 4.

Dose–response curves for restoring sensitivity in Lucena 1 treated with doxorubicin (Dox) as an antineoplastic drug in the absence or presence of (A) compound 5c and (B) compound 7b. In Lucena 1 cells, doxorubicin toxicity was significantly increased when compounds 5c and 7b were co-administered from 0.04 and 0.08 µM, respectively (p < 0.05). The same assay was performed in K562 to discard additional effects other than P-gp. Values are expressed as means ± SE of at least three independent experiments.