CXCL12 and breast cancer: We previously demonstrated that breast cancer patient‐derived CAFs highly expressed a typical myofibroblast marker α‐smooth muscle actin (α‐SMA), secreted elevated levels of a proangiogenic chemokine, stromal cell‐derived factor‐1 (SDF‐1, also known as CXCL12) and promoted the growth of cancer cells in a mouse xenograft model.19