Context
Apoptosis of osteoblasts is a key to controlling osteoblast life span and bone formation, in addition to differentiation of progenitor cells. There are two types of regulators of osteoblast apoptosis: osteotropic hormones and local regulatory cytokines, such as tumor necrosis factor-a, interleukin-1 and -6, insulin-like growth factor-1, and fibroblast growth factor. Although it is well known that bone morphogenic proteins (BMPs) play a pivotal role in the commitment and differentiation of osteoblastic lineage, their role in apoptosis induction remains unknown.