MMP1 and breast cancer: PAR-1 appeared as a good candidate receptor because (i) it is oncogenic in NIH3T3 cells and its activation in various cancer cells has been linked to migration, invasion, and metastasis [43], [63], [64], [65], [66], [67], (ii) MMP-1 and MMP-2 secreted by skin fibroblasts have previously been linked to PAR-1-mediated migration of highly invasive breast cancer cells [43], (iii) and the PAR-1 gene is overexpressed in mammary cancer cell lines selected for strong EMT characters [68].