Changes in the level of expression of Bcl-2 family members during treatment with actinomycin D.

MM cell lines were cultured in IL-6–containing medium without (C) or with the addition of actinomycin D (1 μg/mL) for 2 to 6 hours. In one culture from each cell line, MG115 (10 μM) was added 30 minutes before actinomycin D, and then cells were incubated for an additional 6 hours. At the indicated times, protein extracts were prepared, and equal amounts of total protein were subjected to Western blot analysis. The target of the primary antibody used in each case is indicated along the left margin. In the lane marked Mcl-1/p, the immunizing peptide was preincubated with the anti–Mcl-1 antibody prior to addition to the Western blot filter. Actin levels are included as a control for equal protein loading.