Administration of Noggin suppresses osteogenesis,250,251 and neutralizing Noggin promotes osteoblast differentiation.252 Mice with conditional overexpression of Noggin showed dramatic decreases in bone mineral density and bone formation rates.250,253 However, deletion of Noggin in mature osteoblasts resulted in more osteoclast formation and osteopenia.254 Whether the detrimental impact on bone is attributed to an excessive presence of BMP or whether Noggin plays a BMP-independent role in skeletal homeostasis remains uncertain. Here, NOG is linked to Osteopenia.