In a preclinical study, vaccination against sodium-independent cystine-glutamate antiporter (xCT), the functional subunit of the cysteine/glutamate antiporter system xc-, has been proven effective in the inhibition of mammosphere formation, xenograft growth, and metastasis in EGFR-positive breast cancer cells that overexpressed xCT [162]. Here, EGFR is linked to breast carcinoma.