1. Pre-calculated protein-protein interaction (PPI) data sets. 
2. These PPI data were taken from the STRING database (http://string.embl.de/).
3. All the protein sequences were mapped to the UniProt database by BLAST. 
4. Five organisms including Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, Mus musculus and Homo sapiens were considered.
5. Data format: The 1st column, Interactor A; The 2nd column, Interactor B; The 3rd column, predicted score in STRING database. 
6. Files:
(1) SC.string.ppi: budding yeast PPIs
(2) CE.string.ppi: nematode PPIs
(3) DM.string.ppi: fruit fly PPIs
(4) MM.string.ppi: mouse PPIs
(5) HS.string.ppi: human PPIs
7. Last updated, April 8, 2010. 
