In order to understand the mechanisms underlying age- and osteoporosis-related changes in bone formation, his laboratory discovered several secreted factors derived from BMSCs [e.g., Delta Like Non-Canonical Notch Ligand 1(DLK1), Legumain (LGMN), Cell Migration Inducing Hyaluronidase 1(KIAA1199)], which play a key role in stem cell differentiation and provide a link between bone biology and whole body energy metabolism (14–17). The gene discussed is DLK1; the disease is osteoporosis.