Notably, patients with osteoporosis or age-associated bone loss display a significantly low activity of Wnt/β-catenin signaling in bone marrow mesenchymal stromal cells (BMMSCs), primarily due to the high circulating levels of Dkk1 and Sost (Coulson et al. 2017; Hampson et al. 2013). Here, DKK1 is linked to osteoporosis.