However, searches within the well-characterized genomes of the unicellular organisms Saccharomyces cerevisiae (Baker???s yeast) and Schizosaccharomyces pombe (fission yeast), or invertebrates, such as Caenorhabditis elegans (free-living roundworm) and Drosophila melanogaster (fruit fly) did not reveal any homologs of the GIMAP gene family [4].