FIG. 10.

The proapoptotic Bcl2 family proteins Bax and Bak are required for JNK-dependent apoptosis. (A) Bax and Bak are required for JNK-dependent apoptosis. Wild-type and Bax^−/− Bak^−/− mouse fibroblasts were transfected with empty vector (control) or expression vectors for JNK1 or MKK7-JNK fusion proteins. Cell viability at 40 h posttransfection was examined using a luciferase reporter plasmid. The data presented represent the means ± SD of data obtained for three independent experiments. (B) Endogenous JNK is not required for apoptosis caused by Bax and Bak. Wild-type and Jnk1^−/− Jnk2^−/− mouse fibroblasts were transfected with empty vector (control) or expression vectors for Bax, Bak, or tBid. Cell viability at 40 h posttransfection was examined using a luciferase reporter plasmid. The data presented represent the means ± SD of data obtained for three independent experiments. (C) Bax is not activated by UV radiation in JNK-deficient murine fibroblasts. Wild-type and Jnk1^−/− Jnk2^−/− fibroblasts were exposed to UV radiation (80 J/m²) and incubated (24 h). The cells were fixed and stained with a conformation-specific antibody to Bax and Texas Red-conjugated goat anti-mouse antibody. The Bax antibody stains activated and membrane-targeted Bax but not cytoplasmic Bax. DNA was stained with DAPI (blue).