SLC7A11 and cancer: However, it is believed that intracellular cysteine derived from the transsulfuration pathway generally is not sufficient to cope with the high levels of oxidative stress to which cancer cells are exposed, and therefore most cancer cells still rely primarily on the acquisition of cysteine from the extracellular milieu via SLC7A11 (Chio and Tuveson, 2017; Koppula et al., 2020).