FIGURE 9:

Actin polymerization is required for collagen-induced drug efflux and ABCC1 expression. (A) Cytochalasin B (CB) abrogates collagen-induced F-actin formation. Jurkat cells were left untreated (NT) or activated with collagen (Col) in the presence or absence of CB (10 μM). The F-actin content was assessed by staining with Alexa Fluor 594–conjugated phalloidin (1 μM) and flow cytometry analysis as described in Materials and Methods. (B) Actin cytoskeleton disruption abrogates collagen-induced drug efflux. Jurkat cells were activated or not with collagen (Col) in the presence or absence of CB and then treated with doxorubicin. Intracellular doxorubicin content was then assessed by flow cytometry analysis. (C) Actin cytoskeleton disruption abrogates collagen-induced ABCC1 expression. Jurkat cells were activated or not with collagen (Col) in the presence or absence of CB. ABCC1 expression was then assessed by intracellular staining and flow cytometry as described in Materials and Methods. The results represent mean values ± SD of positive cells (%) times the mean fluorescence from three independent experiments. *p < 0.05 where indicated.