A BMP-Shh negative-feedback loop restricts Shh expression during limb development.

@article{Bastida2009ABN,
  title={A BMP-Shh negative-feedback loop restricts Shh expression during limb development.},
  author={Ma F{\'e}lix Bastida and Rushikesh Sheth and Maria A Ros},
  journal={Development},
  year={2009},
  volume={136 22},
  pages={3779-89}
}
Normal patterning of tissues and organs requires the tight restriction of signaling molecules to well-defined organizing centers. In the limb bud, one of the main signaling centers is the zone of polarizing activity (ZPA) that controls growth and patterning through the production of sonic hedgehog (SHH). The appropriate temporal and spatial expression of Shh is crucial for normal limb bud patterning, because modifications, even if subtle, have important phenotypic consequences. However… CONTINUE READING