For example, current studies have discovered that dormant breast cancers could promote MSC to release exosomes including distinct miRNA such as miR-127, -197, -222, and -223, driving breast cancer cells into quiescence through reducing the expression of CXCL1 (Hanahan and Folkman, 1996; Bliss et al., 2016). Here, CXCL1 is linked to breast cancer.