Shedding light on the distinct functions of proteoglycans

Heparan sulfate proteoglycans (HSPGs) are ubiquitous molecules that are critical for signaling mediated by many growth factors, including members of the Wnt, transforming growth factor-beta, Hedgehog, and fibroblast growth factor families, and are essential for cell specification, axon guidance, and the establishment of morphogen gradients. Although the heparan sulfate modifications of HSPGs are critical, there is much to learn about how the protein cores contribute to the specific signaling functions of these cell-surface and matrix molecules. Recent work has demonstrated that glypican-1 and syndecan-1 expressed by tumor cells have specific roles in FGF2 signaling, affecting their responses to this mitogenic stimulus.