The Glypican (GPC) family of cell surface heparan sulfate proteoglycans is expressed in a tissue specific and developmentally regulated fashion. Expression of Glypican 4 has been reported in the mouse brain at embryonic day 10 and later stages and low during early tubule formation but is up-regulated in mature tubules. Accordingly it is not detected in the midline of the embryo at the initial stage of neural tube closure, suggesting that GPC4 is unlikely to play an essential role in convergent extension in the mouse.