Protein-protein interaction (PPI) extraction has been an important research 
topic in bio-text mining area, since the PPI information is critical for 
understanding biological processes. However, there are very few open systems 
available on the Web and most of the systems focus on keyword searching based on 
predefined PPIs. PIE (Protein Interaction information Extraction system) is a 
configurable Web service to extract PPIs from literature, including 
user-provided papers as well as PubMed articles. After providing abstracts or 
papers, the prediction results are displayed in an easily readable form with 
essential, yet compact features. The PIE interface supports more features such 
as PDF file extraction, PubMed search tool and network communication, which are 
useful for biologists and bio-system developers. The PIE system utilizes natural 
language processing techniques and machine learning methodologies to predict PPI 
sentences, which results in high precision performance for Web users. PIE is 
freely available at http://bi.snu.ac.kr/pie/.