Understanding morphogen activity is one of the longest standing problems in developmental biology. Both the duration of exposure to the secreted morphogen Sonic hedgehog (Shh) and the concentration of Shh are important in determining the fate of cells in the neural tube and in the limb bud. This paper clarifies the relationship between time and concentration in Shh signalling during patterning of the neural tube.
- Eric Dessaud
- Lin Lin Yang
- James Briscoe
