NR4A1 and cancer: On the other side, since miR-9-5p expression seems to be related to invasive and metastatic propensity of cancer cells, the use of miRNA inhibitors in ER negative breast cancer expressing high levels of miR-9-5p may revert this aggressive phenotype and enhance the expression of hormone receptors, inhibiting pathways associated with metastatic behaviour and even rendering patients responsive to hormonal therapies.