*4.1. Reagents and Inhibitors*

Ricin toxin (*Ricinus communis* agglutinin II) was purchased from Vector Laboratories and used at the concentrations noted. Ricin was dialyzed in 1× PBS using 10K MW-cuto ff Slide-A-Lyzer dialysis

cassettes (Pierce, Rockford, IL, USA) prior to experimentation. Cycloheximide (Sigma, St. Louis, MO, USA) was used at a concentration of 500 ng/mL unless noted otherwise. Recombinant human TRAIL (Peprotech, Rocky Hill, NJ, USA), TNF-α (Shenandoah Biotechnology, Warwick, PA, USA), and FasL (Super Fas ligand, Enzo Life Sciences, Farmingdale, NY, USA) were used at a concentration of 100 ng/mL unless noted otherwise. All caspase inhibitors are irreversible and were purchased from ApexBio (Houston, TX, USA). Pan-caspase inhibitor zVAD-fmk, executioner caspase and cathepsin inhibitor zFA-fmk, and caspase-2 inhibitor zVDVAD were each used at a concentration of 50 μM. Caspase-3/7 inhibitor zDEVD, caspase-8 inhibitor zIETD, and caspase-6 inhibitor zVEID were each used at a concentration of 30 μM. Caspase-1 inhibitor zYVAD-fmk and caspase-9 inhibitor zLEHD-fmk were each used at a concentration of 10 μM. Necrostatin-1s (EMD Millipore, Burlington, MA, USA) was used at a concentration of 50 μM. Bax-inhibiting peptide v5 (EMD Millipore) was used at a concentration of 100 μM. E64d was used at a concentration of 10 μM. Cathepsin inhibitor 1 (CATI-1, ApexBio) was used at a concentration of 20 μM. N-acetylcysteine (Sigma) was used at a concentration of 10 mM.
