TIMP3 and breast cancer: As TIMP3 expression is down-regulated or lost in several tumor types [24-26], and adenoviral transfer of TIMP3 into HeLa, HT1080 fibrosarcoma, and melanoma cells reduces their invasiveness and stimulates apoptosis[27,28], we tested whether miR-21 may be impacting TIMP3 expression in primary breast cancer specimen as well as four breast cancer-derived cell lines.