Cells were treated GST-TRAIL or drozibumab as indicated in the text and figure legends. For caspase inhibition, cells were preincubated with 100 uM ZVAD-FMK or DMSO for two hours and subsequently incubated overnight with 2500 ng/ml drozitumab or 2500 ng/ml drozitumab plus 10 μg/ml F(ab’)2. Caspase activity was assessed using the Caspase-Glo® 3/7 assay system (Cat # G8092, Promega Corporation, Madison, WI) and/or Caspase-Glo® 8 assay system (Cat # G8202, Promega Corporation, Madison, WI) as previously described [27 (link)]. Three independent experiments normalized to the control cells +/− SE were performed.