Intriguingly, gamma-glutamyltransferase 1, an enzyme that cleaves extracellular glutathione, halts cystine deprivation-induced GSH depletion and ferroptosis in glioblastoma with high cell density, indicating a novel pathway mediating GSH-GPX4 axis distinct from cystine deprivation or inhibition of cystine uptake133. The gene discussed is GPX4; the disease is glioblastoma.