In contrast to the cathepsin-mediated increase in resorption, DKK1 functions as a potent inhibitor of the Wnt/β-catenin pathway, a critical signaling cascade for osteoblast differentiation and bone formation [26]; elevated DKK1 suppresses osteoblastogenesis and bone formation and its role has been well-established in osteoporosis [27]. The gene discussed is CTSS; the disease is osteoporosis.