Endo g

18α-Glycyrrhetinic acid (18α-GA), 4,6-diamidino-2-phenylindole (DAPI), dimethyl sulfoxide (DMSO), N-acetyl-l-cysteine (NAC), propidium iodide (PI) and trypsin-EDTA were obtained from Sigma Chemical Co. (St. Louis, MO, USA). RPMI-1640 medium, fetal bovine serum (FBS), l-glutamine and antibiotics (penicillin-streptomycin) were purchased from GIBCO^®/Invitrogen Life Technologies (Carlsbad, CA, USA). Primary antibody against PARP, caspase-3,-8, -9, AIF, Endo G, Bid, Bax, Bcl-2, Bcl-xL, cytochrome c, Fas, Fas-L and peroxidase conjugated secondary antibodies were purchased from Cell Signaling (St Louis, MO, USA). 18α-GA was dissolved in DMSO. Cell culture grade DMSO was used for vehicle at 0.1%.

PW06 (Figure 1) was generated by Dr. Jin-Cherng Lien (College of Pharmacy, China Medical University, Taichung, Taiwan). DAPI, propidium iodide (PI), and trypsin-EDTA were purchased from Sigma Chemical Co. (St. Louis, MO, USA). Dulbecco's modified Eagle's medium (DMEM), fetal bovine serum (FBS), L-glutamine, and penicillin-streptomycin were purchased from GIBCO®/Invitrogen Life Technologies (Carlsbad, California, USA). Primary antibodies against -Bid, -Bax, -p53, -Bcl-2, -Bcl-xL,-XIAP, -cytochrome c, -caspase-9, -caspase-3, -caspase-8, -PARP, -Fas, -Endo G, and peroxidase-conjugated secondary antibodies were purchased from Cell Signaling Technology, Inc. (Beverly, MA, USA). Alternatively, primary antibodies against β-actin, Bcl-xL, Bak, and AIF were purchased from Sigma-Aldrich (St. Louis, MO, USA).

Celastrol with purity greater than 98%, N-Acetyl-L-cysteine (NAC), SP600125, 3-Methyladenine (3-MA) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Dulbecco's Modified Eagle Medium (DMEM), RPMI 1640 Medium, fetal bovine serum (FBS), penicillin, streptomycin, PBS and 0.25% trypsin were purchased from Gibco/BRL (Gaithersburg, MD, USA). The broad-spectrum caspase inhibitor (z-VAD-fmk) was obtained from Millipore (Billerica, MA, USA). Caspase-8 specific inhibitor (z-IETD-fmk) and caspase-9 specific inhibitor (z-LEHD-fmk) were purchased from BioVision (Mountain View, CA, USA). Antibodies against TRAIL and DR4 were obtained from ProteinTech Group (Chicago, IL, USA). Antibodies against caspase-3, caspase-8, caspase-9, poly (ADPribose) polymerase (PARP), DR5, Bid, Fas, FasL, phospho-JNK, JNK, LC3B, phospho-Cdc2, Cdc2, phospho-Cdc25C, Cdc25C, cyclin B1, phospho-Chk2, Chk2, p21, AIF, Endo G and GAPDH were purchased from Cell Signaling Technology (Beverly, MA, USA).