CDK4 and breast cancer: miR-222 and miR-223 were upregulated in exosomes isolated from dormant BC-induced BMSCs and in turn, decreased CDK4, Cyclin D1 and p21WAF1 expression to initiate cycling quiescence of cancer cells and produce resistance to carboplatin, whereas the antagomiR-222/223 could reverse the quiescent phenotype of BC [104].