Overexpression of Mcl-1 confers resistance to actinomycin D.

(A) Pools of 8226 cells were expanded after infection with recombinant lentiviruses expressing EGFP, Mcl-1, or HA–Mcl-1. Cells were cultured for the indicated times in medium containing actinomycin D, and protein extracts were subjected to Western blot analysis by means of antibodies with specificities as indicated along the left margin. (B) The 8226–EGFP or 8226–Mcl-1 pools were cultured in normal growth medium (control) or in medium containing actinomycin D for 6 hours. Cytospin preparations were assayed in situ by TUNEL and counterstained with Hoechst 33342. Identical fields are shown for each TUNEL/Hoechst pair (magnification, × 400).