Osterix (Osx)-Expressing Osteoblastic Progenitor Cells Support Hematopoietic Cell Growth and Differentiation. When osteoblastic progenitor cells are induced to delete either the sbds (associated with Shwachman–Bodian–Diamond syndrome) or dicer (necessary for microRNA formation) gene in mice, the mice develop a form of myelodysplasia that can progress to AML. In contrast, when these genes are deleted only in mature osteocalcin (Ocn)-expressing osteoblasts, there is no effect on hematopoiesis.