To fit or not to fit: death decisions from morphogen fields.

The transforming growth factor-ß (TGF-ß)-type morphogens are conserved throughout the animal kingdom. TGF-ß-type molecules form spatial concentration gradients whose length scales with the size of growing, developing organs. Scaling of these morphogens can also be mediated by death, adjusting the size of the tissue to the range of the gradient. Death-mediated scaling might provide a molecular toolbox exploited by cancer cells.