Decreased intracellular retention of epirubicin in PC-3/ Res cells. (A) Fluorescent microscope images of PC-3/Wt and PC-3/Res cells. Cells were incubated with 5μM epirubicin for 2 h and then allowed to efflux for 1 h in drug free media. Bar, 50µm. (B) Intracellular fluorescent intensity of epirubicin was quantified using Image J Software. Error bars represent standard error of mean, n=30; ****P ˂ 0.0001.