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Many growth factors that promote the formation of bone-forming cells called osteoblasts are thought to act through a transcription factor called core binding factor 1 (Cbfa1). Mice lacking Cbfa1 fail to form any mature osteoblasts or bones, and experiments with a dominant negative form of Cbfa1 have suggested that the protein is important in regulating osteoblast functions such as matrix formation and mineralization.2 P: d1 I1 G# V4 [, {+ ^+ D C
3 X# e T. O6 X" |: bNow, Liu et al. (page 157) find that mice overexpressing Cbfa1 in their osteoblasts have weak bones and multiple fractures within a few weeks after birth. Immature osteoblasts accumulate, suggesting that the excess Cbfa1 inhibits a late stage of osteoblast maturation. Thus, Cbfa1 is essential early in maturation but must then be downregulated to allow final maturation.(More marrow and weaker bones in mice wit) |
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