CXCL12 and breast carcinoma: In a xenograft model of breast cancer an implanted biomaterial (PLG) scaffold recruited circulating metastatic breast cancer cells (MDA-MB-231BR)42,49 and human breast cancer brain metastasis derived three-dimensional CAFs aggregates expressed significantly higher levels of CXCL12 and CXCL16 than CAFs aggregates generated from primary breast tumors or normal breast, suggesting that chemokine modulation is crucial in regulating metastasis1.