The importance of Wnt/β-catenin signaling in osteogenesis has been highlighted by the fact that (i) loss-of-function mutations in Lrp5, a co-receptor for Wnt/β-catenin signaling, cause osteoporosis and (ii) sclerostin, an osteocyte-derived inhibitor of Wnt/β-catenin signaling, suppresses bone formation [27]. Here, LRP5 is linked to osteoporosis.