In summary, the bulk of preclinical and clinical findings of this study expand our current understanding of the function of p140Cap in BC, providing substantial evidence that tumor-autonomous mechanisms of tumor suppression, such as the restriction of the TIC compartment through β-Catenin inhibition, are inextricably intertwined with local and systemic tumor-extrinsic effects that antagonize the establishment of tumor immune tolerance and inhibit tumor progression and metastasis. This evidence concerns the gene SRCIN1 and breast cancer.