Figure 2.

Inhibition of TAK1 triggers two caspase 8 activation pathways through induction of the RIP1-FADD-caspase 8 complex as well as FLIP degradation. (a) Caspase 8 activity in wild-type MEFs treated as indicated for 4 h. ^†P<0.05 versus Control; ^#P<0.05 versus 5z-7 plus TNF. (b) Western blots for the indicated proteins following IP with an anti-FADD antibody from extracts of MEFs treated as indicated for 1 h. * indicates cleaved caspase 8. (c) Western blots for FLIP and α-tubulin from extracts of MEFs treated as indicated. * indicates cleaved FLIP. (d) Caspase 8 activity in FLIP+/+ and FLIP-/-, MEFs treated as indicated for 2 h. ^†P<0.05 versus Con; ^#P<0.05 versus FLIP+/+. (e) Cell death assessed by PI staining of cells treated as in d. ^†P<0.05 versus Con; ^#P<0.05 versus FLIP+/+. (f) Western blots for the indicated proteins from FLIP+/+ and FLIP-/-, MEFs treated as indicated for 4 h. (g) Western blots for the indicated proteins from H9c2 myocytes infected with β-gal or FLIP adenoviruses for 24 h, then treated as indicated for 4 h. CHX, cycloheximide