Fig. 7From: Doxorubicin treatment modulates chemoresistance and affects the cell cycle in two canine mammary tumour cell linesMultidrug Resistance Direct Dye Efflux Activity in CIPp and CIPm. Cells were loaded with DiOC2(3) and incubated at 4 °C, or at 37 °C in the presence or absence of Vinblastine for 15 min, 1, 4 and 24 h. After washing and PI staining, cells were analyzed by flow cytometry and dead cells were excluded from analysis. Cells incubated at 4 °C (negative control - N) exhibit high fluorescence, as P-gp and BCRP are inactive at low temperatures and the cells retain the dye. Cells incubated at 37 °C (positive control - P) have a progressively lower fluorescence over time, as P-gp and BCRP are active and cells efflux the dye. Cells incubated at 37 °C in the presence of Vinblastine (V) that specifically effluxes via P-gp, have higher fluorescence compared to control cells, as Vinblastine competes with the dye for efflux by P-gpBack to article page