Bortezomib (Bort) induces FADD and caspase-8 (Cas8) in cancer cells, and caspase-8 is required for Sp degradation. ANBL-6 and RPMI 8226 cells (A) and L3.6pL and SW480 cells (B) were treated with different concentrations of bortezomib for 24 hours, and whole-cell lysates were analyzed by Western blots for caspase-8 activation (cleavage). ANBL-6 and RPMI 8226 cells (C), and Panc1, L3.6pL, and SW480 cells (D) were treated as described in (A) and (B), and whole-cell lysates were analyzed by Western blots for the induction of FADD. (E) ANBL-6, RPMI 8226, L3.6pL, and SW480 cells were treated with bortezomib alone and in combination with an oligonucleotide targeted to caspase-8, and whole-cell lysates were isolated and analyzed by Western blots.