Table 1.

Reference databases used for data retrieval during the investigation

Database	Description	URL	Statistics	Data extracted
Uniprot [20]	comprehensive, high-quality and freely accessible resource of protein sequence and functional information.	http://www.uniprot.org	220,325 entries	function,, post-translation modification, location, developmental stage, etc.
I2d [21]	on-line database of known and predicted mammalian and eukaryotic protein-protein interactions	http://ophid.utoronto.ca/	424,066 entries (92,561 for human)	protein interaction
Reactome [22]	curated resource of core pathways and reactions in human biology.	http://www.reactome.org	928 pathways for human	Pathway
PID [23]	curated pathway and interactions	http://pid.nci.nih.gov/	133 pathways	Pathway