 The proteins from these in turn control the pair-rule genes, which in the next stage set up 7 bands across the embryo's long axis.Finally, the segment polarity genes such as "engrailed" split each of the 7 bands into two, creating 14 future segments.This process explains the accurate conservation of toolkit gene sequences, which has resulted in deep homology and functional equivalence of toolkit proteins in dissimilar animals (seen, for example, when a mouse protein controls fruit fly development).