Mcl-1 knockdown promotes cleavage of caspase 3 in non-adherent melanoma cells. WM793 cells were transfected with control, Mcl-1, Bcl-2 or Bcl-XL siRNA, as indicated. (A) Seventy-two hours post-transfection, cell lysates were analyzed by Western blotting for Mcl-1, Bcl-2 or Bcl-XL. Total ERK1/2 was used as a loading control. (B) 72 hours following transfection, WM793 cells were serum starved for 24 hours and then replated onto agar-coated dishes in serum-free medium. After 48 hours, cells were analyzed for cleaved caspase 3 using flow cytometry. The fluorescence intensity is measured on the x axis and cell counts on the y-axis. The percentages of cells staining positive in each condition are indicated. (C) Quantitation of the data from (B) is presented as the average percentage of cells staining positive for cleaved caspase 3 from three independent experiments.