Figure 5 Oleic acid induced TRAIL sensitisation is DR5 dependent. (A) Western blot analysis was performed for DR5 and DR4 expression using whole cell lysates from Huh 7 cells transfected with respective siRNAs. The specificity and effectiveness of each siRNA is demonstrated. In cells treated with siDR4 a decrease in DR4 level was observed, DR5 levels were unchanged. In contrast, in cells treated with siDR5 a decrease in DR5 level was observed, DR4 levels were unchanged. Scrambled siRNA was used as control. (B) Apoptosis was assessed morphologically in cells transfected with siDR5 and siDR4. Oleic acid treatment sensitised to TRAIL cytotoxicity. This was abrogated in siDR5 transfected cells (p<0.05) and unchanged in siDR4 transfected cells. (C) Caspase 3/7 activity was assessed in cells transfected with siDR5 and siDR4. Oleic acid treatment (200 μM) sensitised to TRAIL cytotoxicity; this was JNK dependent, and the sensitisation was unchanged in siDR4 transfected cells (p<0.05). In siDR5 transfected cells TRAIL sensitisation was abolished and predictably unchanged in the presence of JNK inhibitor, SP600125.