SLC7A11 and cancer: Intracellular cysteine can be recovered by ab initio biosynthesis or by protein degradation, and most cancer cells rely primarily on the cystine transporter protein system Xc- (consisting of the catalytic subunit SLC7A11 and the chaperone subunit SLC3A2) to obtain cystine from the extracellular environment, which is then converted to cysteine in the cytoplasm via a reduction reaction that consumes NADPH; cysteine is then used for the synthesis of glutathione (and other biomolecules) (Liu, Xia & Huang, 2020).