Westernblot analysis of Caspase-8 activation and PARP-cleavage. Lysates were prepared as described in methods. In six tumour cell lines(Colo 205, NCI H460,, HCT-15, MDA MB 231, FaDu and SCC-4) caspase-8 and PARP cleavage was analysed in untreated cells (lane 1), 24 h after treatment with TRAIL 0,1 ng/ml (lane 2) and 10 Gy alone (lane 3), after simultaneous (lane 4) and sequential application (lane 4) of combined therapy. Every cell line shows a different cleavage pattern according to the rate of apoptosis induction. β-Actin staining was used as loading control. The mapped blots represent each one of three independently performed immunoblots.