CXCL12 and breast cancer: Lim et al. [80] showed that exosomal miRNAs derived from bone marrow stroma (miR-127, miR-197, miR-222, and miR-223) inhibit breast cancer cell proliferation via direct targeting of the CXCL12 chemokine gene, leading to the induction or maintenace of a dormant state of breast cancer cells.