In contrast, constitutive MT1-MMP-mediated DDR1 shedding was found to regulate collagen-induced signaling when DDR1 and MT1-MMP were co-expressed in COS1 cells, whereas MT1-MMP was suggested to be one of several DDR1 sheddases and regulators in HC1806 breast cancer cells [64]. Here, DDR1 is linked to breast cancer.