Comparison of Nix and Bcl-xL protein catabolism. After 12 days in culture, 50 μM lactacystin (Lac) or 200 μM cycloheximide (CHX) was added to inhibit proteosomal degradation or protein translation, respectively. Whole cell extracts were prepared from cells on culture day 14 and were compared with control samples collected on days 12 and 14. Western blot analyses for Nix and Bcl-xL are shown for comparison.