FIG. 3.
(A) Stress stimuli displace endogenous FAST from mitochondria. HeLa cells were left untreated or were treated with UV irradiation (10 mJ/cm2 followed by 0.5 or 1 h recovery) or anti-Fas antibody (1:200 dilution from culture supernatants) for 6 h before being processed to obtain pellets enriched in mitochondria (P20) and corresponding supernatants (S20). Individual fractions were processed for Western blotting analysis with anti-FASTN antibody or anti-BCL-XL antibody. (B) Fas ligation interrupts FAST/BCL-XL interaction. HeLa cell extracts prepared from cells cultured in the absence or presence of anti-Fas antibody were processed for coimmunoprecipitation with either rabbit anti-BCL-XL antibody or an isotype-matched control antibody (rabbit anti-Myc). Immunoprecipitates were then processed for Western blotting analysis with anti-FAST-N antibody or mouse anti-BCL-XL antibody.