MMP13 and breast cancer: Intrigued by our previous work showing that siRNA-mediated silencing of RSU-1, using a commercially available pool of siRNAs that targets both isoforms, leads to reduced invasive capacity of BC cells accompanied by inhibition of urokinase Plasminogen Activator (uPA), and metalloproteinase-13 (MMP-13)22, we set out to further investigate the role of RSU-1 isoforms in BC cell metastasis.