Fig. 5.

Obatoclax overcomes MCL-1-mediated resistance to bortezomib in melanoma cells. (Top) Mouse melanoma B16-F1 cells were transfected with luciferase siRNA or mouse Mcl-1 siRNA for 24 h followed by a 24-h treatment with bortezomib at the indicated concentrations. Total cell lysates were analyzed by immunoblot for Mcl-1 expression. (Middle) As in Top, except that the percentage of cells that incorporated annexin V was determined by flow cytometry. (Bottom) B16-F1 cells were incubated with bortezomib alone or in combination with 50 nM obatoclax for 24 h and apoptosis (annexin V staining) determined as in Middle.