PIR and breast cancer: In addition, Hashim et al. found that in breast cancer cells, piR-34377, piR-35407, and piR-36743 are up-regulated, whereas piR-36026, piR-36249, piR-36318, and piR-36712 are down-regulated—suggesting potential regulatory roles in the cell cycle, apoptosis, cell–cell interactions, and DNA replication and repair [155].