For example, Boire et al. showed that MMP1 activation of PAR1 promoted invasiveness and tumorigenesis of breast cancer cells in xenograft models19; Villares et al. showed that in-vivo treatment of melanoma-bearing mice with PAR1 siRNA inhibited melanoma growth and metastasis22; and Adams et al. showed that PAR1 expressed by tumor stromal cells promoted colon cancer growth in vivo22,23. Here, MMP1 is linked to melanoma.