Breast cancer stem cells secretomics; identifying DKK1 as a CSC-secreted protein inducing SLC7A11 expression; a combination of erastin (xCT inhibitor) and gallocyanine (DKK1 inhibitor) for inhibiting experimental breast cancer metastases of MDA-MB-231cells xenografted in nude mice. This evidence concerns the gene DKK1 and breast carcinoma.