CXCR4 and breast cancer: Indeed, the restoration of the miR-302a expression has been shown to inhibit the invasive ability and metastasis both in vitro and in vivo by down-regulation of CXCR4 expression [61], whereas the ectopic expression of miR-326 sensitized multidrug-resistant BC cells to chemotherapy by down-regulation of MRP-1 expression [62].