Growth, hedgehog and the price of GAS.

Embryonic development in a given species is orchestrated by genes regulating growth and differentiation in a stereotyped and conserved manner, resulting in embryos of consistent size and shape. Several signaling pathways, including that of Sonic Hedgehog (SHH), have been implicated in these processes. Recent experiments with Gas1 indicate that it may act as a growth-inducing gene, challenging its previous function as a gene specifically involved in growth arrest. Moreover, GAS1, a GPI-linked membrane protein, can bind SHH, suggesting an interacting link between growth and patterning through SHH and GAS1.