(a) Western blot analysis of PARP cleavage and caspase 3 activation in REN cells following transfection with SCR, FLIP(S), FLIP(L) and FLIP(T) siRNA. Cells were treated with 10 μM AT-IAP, 10 ng/ml TNFα and a combination of AT-IAP and TNFα for 24 h. (b) (i) Western blot analysis of c-FLIP in JU77 cells transfected with SCR, FLIP(S), FLIP(L) and FLIP(T) siRNA for 48 h. (ii) Flow cytometry determination of sub G0/G1 apoptotic populations of JU77 cells following transfection with SCR, FLIP(S), FLIP(L) and FLIP(T) siRNA and treatment with 10 μM AT-IAP, 10 ng/ml TNFα and a combination of AT-IAP and TNFα for 24 h. (c) AlphaScreen assay of protein/protein interaction between recombinant GST-tagged FADD and FLAG-tagged wild-type (WT) and F114A mutant FLIP(S) proteins. (d) Cell viability assays in control (EV), wild-type (WT) and F114A mutant FLIP(S) overexpressing cell lines following transfection with SCR siRNA or an siRNA targeting the common 5′-UTR of the FLIP(L) and FLIP(S) transcripts (5′UTR FLIP(T)) for 24 h followed by treatment with 10 μM AT-IAP, 10 ng/ml TNFα and a combination of AT-IAP and TNFα for 48 h