FGF mediated Sulf1 regulation.

FGF signalling is critical for normal embryonic development. Sulf1 has been shown to inhibit FGF activity. The role of FGF4 in Sulf1 regulation was investigated during digital development of the quail autopod. Implantation of FGF4 beads in both the interdigit and at the tip of digit III differentially up-regulated Sulf1 as also confirmed in micromass cultures. FGF4 inhibited interdigital mesodermal apoptosis in a concentration dependent manner. The FGF inhibitor, SU5402, inhibited Sulf1 expression when placed in the interdigital mesoderm. However, when placed at the digital tip, SU5402 induced an ectopic domain of Sulf1 expression and inhibited further phalange formation.