Tumor cell uptake of cystine is impaired by interferon-gamma produced by CD8+ T cells.166 Cystine levels, in turn, appear to mediate glutathione activity, which helps to inhibit lipid oxidization and ferroptosis.167 When cyst(e)inase is used to degrade cystine, tumor cells are more likely to undergo immune-mediated ferroptosis. The gene discussed is CD8A; the disease is neoplasm.