Efflux activity for Hoechst33342.

<p>(A) The OSK-SW480 cells included a population of cells unlabeled by 5 µg/ml of Hoechst33342 with the co-administration of 50 µM of verapamil (VM). We designated the cells unlabeled by Hoechst33342 without VM and with 50 µM of VM as V0-cells and V50-cells, respectively. The left panel shows representative dot plots of labeled and unlabeled cells at day 10 after transduction. The right panel shows the results of three independent experiments. The V0 subpopulation was increased in the O- and OSK-SW480 cells. The V50-cells were obviously seen in the OSK-SW480 cultures. The error bars indicate the SD (n = 3). *P<0.05, **P<0.01, Dunnett's test. (B) Dye efflux activity at day 10 (left panel) and day 28 (right panel) after transduction. The V50-cells disappeared under the treatment with the co-administration of 250 µM of VM even in the OSK-SW480 cells. The proportion of the OSK-V50 cells decreased with time.