Caspase-Glo® 3/7 assay

1x10⁴ cells/well were treated with 5, 10, and 25 nM bortezomib for 1–72 h and analyzed for caspase 3/7 activation using the Caspase-Glo^® 3/7 Assay (Promega) according to the manufacturer´s protocol. Briefly, Caspase-Glo^® reagent was added 1:1 to sample volume into each well and incubated at room temperature for 30 min protected from light. Blank values were subtracted from the experimental values to exclude background luminescence and negative controls were used to determine basal caspase activity. Luminescence of each sample was measured using a Luminometer (LUMIstar; BMG Labtech, Ortenberg, Germany). Results were expressed as the mean from two independent experiments (n = 2, measured in biological quadruplicates) and error bars represent the S.D.