Once the basic components of signalling systems had
been identified in model organisms such as C. elegans
and Drosophila, a first overview of the evolutionary
alterations of signalling pathways was revealed by looking
at the signalling gene repertoire in other species.
However, a comprehensive analysis of the evolution of
signalling pathways is hampered by the disparity of the
sequence availability for different organisms. Wholegenome
sequences are available for some medically
important organisms