In breast cancer, COMP expression was shown to expand the population of cancer stem cells via bridging Notch3 with Jagged1, resulting in the activation of the Notch pathway (7).In the cartilage and presumably tumor tissue, COMP binds to collagen fibers, organizes them, and thus makes the cartilage denser and stiffer (4). The gene discussed is COMP; the disease is breast carcinoma.