ERBB2 and breast cancer: To further investigate the effects of SLC7A11 inhibition or cysteine limitation on trastuzumab primary-resistant HER2-positive breast cancer, JIMT1 xenograft mouse models were generated and then treated with different strategies, including DMSO, trastuzumab, erastin, cysteine starvation, trastuzumab plus erastin, and trastuzumab plus cysteine starvation (Figure 4A).