Procaspase-8 deficiency greatly decreases radiation-induced apoptosis in FN attached cells.

<p>(a) Expression of procaspase-8, FADD and β-actin was analyzed by Western blotting. Procaspase-8 negative (Casp-8N), FADD negative (FADD-N) and Jurkat A3 cells were irradiated with 10 Gy in suspension or under adhesion to 100 µg/cm² FN. (b) Casp-8N, FADD-N and Jurkat A3 cells were exposed to mAb TS2/16 or mAb13 (1 µg/ml; anti rat IgG1 as control) for 1 h or 20 µM caspase-8 (IETD-fmk), caspase-3 (DEVD-fmk), pan-caspase inhibitor (zVAD-fmk) or 10 µM Ly294002 for 30 min when adhered to 100 µg/cm² FN. Subsequently, cells were treated with 10 Gy or 300 ng/ml FasL. After 48 h, the number of apoptotic cells was determined by DAPI staining and counting. Columns represent mean±s.d. (n = 3). Statistical analysis was performed by comparing treatment conditions versus controls. *<i>P</i><0.01.