Fig. 2

Framework of our PPI extraction system. Our system consists of two phases. First, training set is divided into subsets based on presence of significant keywords and the feature position of keyword. Second, after cross-validation is performed on the training data to assess the contribution levels of four groups, which consist of related features, feature selection is performed automatically through our three approaches (BEST1G, U3G, O2G). Finally, the k-NN classifier is used to classify candidate PPI pairs of test data