CAF mediated CXCL12 expression is now well described to play an important role in suppressing anti-tumour immunity, this was recently identified as a defining feature of the “CAF-S1” immunosuppressive subset of breast cancer myCAF [22] and blocking the interaction between CXCL12 and its cognate receptor CXCR4, with a clinically approved inhibitor (AMD3100), has shown efficacy in pre-clinical models [44, 45]. This evidence concerns the gene CXCL12 and breast cancer.