CXCR4 and cancer: On overall, these results suggest that a permissive tumor microenvironment in the primary tumor and SLNs, characterized by EMT features such as the activation of CXCR4/CXCL12 axis and the presence of protumor M2 TAMs, can sustain the aggressiveness of cancer cells and support their metastatic dissemination in luminal B BC.