TIMP3 and breast cancer: As tissue inhibitors of metalloproteinases (TIMPs) contain a consensus miR-21 binding site (http://targetscan.org/; http://pictar.mdc-berlin.de/; http://microRNA.org), and reduced expression of TIMP3 in breast cancer tissue has been associated with poor disease-free survival[17], we sought to determine the role of miR-21 in breast cancer invasion, and to identify whether miR-21-mediated invasion might be regulated via TIMP3.