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		the area most effected by SU5402 and its reduction of FGF signaling. Other regions are likely to have been effected due to the strength of SU5402, but there was no conclusive evidence for these defects. Results could have been dependent on time of treatment administration, dosage size, and repetition of treatments. It is possible that at different times of treatment could have effected various developmental processes. The amount of dosage could have had an effect on noticeable defects and repetition of dosages could have caused greater damage by not allowing the chicken embryos to recover. A .............................B Figure 4. Proposed Models. A)In the craniofacial region SHH induces fgf8 which subsequently downregulates shh. We propose that interfering with FGF signaling resulted in increased levels of shh expression in the craniofacial region. B) We propose that interfering with FGF signaling resulted in failure of the shh autoregulatory mechanism and thus over expression of shh in the limb buds.