PAR1 was reported to transactivate EGFR not only in vascular smooth muscle cells (Kanda et al, 2001) and in cardiac fibroblasts (Sabri et al, 2002), but also in colorectal (Darmoul et al, 2004) and in breast cancers (Arora et al, 2008) through a variety of different mechanisms, showing that the two pathways can reciprocally influence their activities. This evidence concerns the gene EGFR and breast cancer.