there are proteins called Gli1, Gli2, and Gli3 that affect ventral hindbrain development, and are also required for motoneuron development and correct neural patterning in the hindbrain. However, how important are they and what their specific roles are was unclear. By mutating the proteins Gli2 and Gli3, which were especially studied, it was found that Gli2 and Gli3 contain both activation and repression domains, while Gli1 only had activation domains, which were entirely transcriptional. Gli2 was also found to be a stronger activator while Gli3 was a strong repressor. Gli2 and Gli3 had overlapping functions that concerned the patterning of the ventral spinal cord which was important for correct organization and formation of the motoneurons. This was shown when mutation of the Gli3 protein showed only a slight decrease in expression of Olig2, while when the Gli2 protein was mutated, the expression of Olig2 was not detected. Olig2 is normally expressed in the ventral area of the neural tube. Mutations in the Gli2 protein causes more severe damage in the ventral patterning of the hindbrain than that of the spinal cord. This shows that Gli2 performs different functions in the hindbrain that Gli3 is unable to substitute. Gli2 and Gli3 in a developing hindbrain also have distinct functions in the Shh (sonic hedgehog) signal transduction. This is caused by differential modulation of gene expression that is specific to each rhombomere. Finally, studies have shown that in rhombomere 4, the ventral patterning is less affected by the mutation of Gli2. This shows that this particular rhombomere has different requirements for Gli proteins. The Hox gene also has been shown to play a part in the formation of the cranial motor nerves. The fate of a rhombomere has been shown to be affected by differential expression of the Hox gene. With mutations in the Hox gene, the cranial motor nerves formed in different locations than normal or simply did not form altogether. One possibility for this was that the Hox gene was somehow involved in regionalization within the neural tube, and that expression of this particular gene correlated with the amount of migration that occurred. However, no correlation could be found. Many studies showed small amounts of correlation, but there were equal amounts showing a complete lack of correlation. The amount of correlation that occurred was not enough to draw a concrete conclusion from. This, however, could have happened because studies have