Sulfasalazine

Riluzole (#0768), L-quisqualate (#0188), Sulfasalazine (#4935), S-4-carboxy-phenylglycine (S-4-CPG) (#0322) were purchased from Tocris Bioscience (Minneapolis, MN, USA). G418 (#11811031) was purchased from Gibco (Invitrogen, Carlsbad, CA, USA). Anti-xCT antibody (1:1000, #PA1–16893) antibody was purchased from Pierce Biotechnology (Rockford, IL, USA). Anti-Flag tag antibody was purchased from Origene (1:1000, #TA100011). Anti-GAPDH (1:1000, #5174) and anti-β-actin (1:1000, #4970) antibodies were obtained from Cell Signaling Technology (Danvers, MA, USA).

All drugs and supplemented metabolites were added at initiation of starvation, unless otherwise stated. BHAM (150 μM–1.5 mM), oligomycin (10 μM), FCCP (100 nM–5 μM), rotenone (100 nM–1 μM), succinate (10 mM), ascorbate (10 mM), TMPD (100 μM), glutamate (10 mM), malate (10 mM), antimycin A (10 μM), ADP (4 mM), l-cysteine (100 μM–2 mM), cystine, (0.05–1 mM) N-acetyl cysteine (0.5–10 mM), reduced GSH (1–20 mM), 2-deoxyglucose (1–10 mM), koningic acid (10–20 μM), glucose (1–20 mM), NH₃ (1–5 mM), NH₄Cl (1–10 mM), 3-methyladenine (1–10 mM), MG132 (10 μM), l-buthionine sulfoximine (100 μM–1 mM) and erastin (100 μM) were all from Sigma. Bafilomycin (10–100 nM) was from Cell Signaling. Rapamycin (20–500 nM) was from LC Laboratories. Sulfasalazine (1 mM) was from Tocris Bioscience. MitoParaquat (1–10 μM) was from Abcam. We diluted 10× essential amino acids from 50× MEM amino acids solution (ThermoFisher), for final concentrations of 6 mM l-arginine hydrochloride, 1 mM l-cystine, 2 mM l-histidine hydrochloride-H₂O, 4 mM l-isoleucine, 4 mM l-leucine, 4 mM l-lysine hydrochloride, 1 mM l-methionine, 2 mM l-phenylalanine, 4 mM l-tryptophan, 2 mM l-tyrosine and 4 mM l-valine.