Figure 7.
The disappearance of Mcl-1 is a required upstream event for UV-induced apoptosis. (A) After UV treatment, mitochondria and S100 were isolated from vector control (lanes 1-4) and two independent Flag-Mcl-1-overexpressing lines: line 120 (lanes 5-8) and line 123 (lanes 9-12). The levels of Mcl-1, Bcl-xL, Bax, and cytochrome c oxidase were measured in the mitochondria. The levels of Mcl-1, Bcl-xL, cytochrome c, and cleaved caspase-3 were measured in the cytosol. (B) Mcl-1 levels were analyzed in mitochondria and S100 fractionated from Vector (lanes 1-3) or Flag-Bcl-xL-overexpressing (lanes 4-6) cells treated with UV for 1 h (lanes 2,5) or 4 h (lanes 3,6). (C) HeLa cells that stably express the Neo vector (lanes 1-5) or Flag-Bcl-xL (lanes 6-10) were left untreated or UV-treated and harvested between 1 and 6 h later for mitochondria and S100. The levels of Flag-Bcl-xL, Bcl-xL, and Bax were determined in the S100 and mitochondria. Mitochondria were also used to evaluate Bax oligomerization.