Indeed, osteoprotegerin is not induced in Notch3em1Ecan mice explaining their RANKL-dependent resorptive phenotype, is induced in RosaNotch3 bone marrow stromal cells, possibly explaining the gain in cancellous bone, and is suppressed in RosaNotch3 osteocytes possibly explaining the cortical bone porosity and osteopenia of mice overexpressing NOTCH3-NICD. The gene discussed is NOTCH3; the disease is Osteopenia.