Fig. 5.

Verification of P-gp transport activity in 4T1 cells and the effect of P-gp blockage on cellular uptake, efflux and toxicity of Nano-DOX and DOX. a Efflux of rhodamine-123 (R123), a specific P-gp substrate, from 4T1 cells and the effect of verapamil (VRP), a specific P-gp inhibitor, on R123 efflux. b Efflux of DOX from 4T1 cells and VRP’s effect on DOX efflux. c VRP’s effect on the uptake of Nano-DOX and DOX by 4T1 cells. d VRP’s effect on the efflux of Nano-DOX and DOX from 4T1 cells. e, f VRP’s effect on apoptosis in 4T1 cells treated with Nano-DOX or DOX (All experiments in this section were performed in vitro and data were acquired through FACS.) In FACS analysis, geometric means were used to quantify fluorescence intensity. Values were mean ± SD (n = 3, *p < 0.05, **p < 0.01)