Principal components analysis plot (PCA) of the mouse stem cell dataset.

<p>Proteins are clustered according to their density gradient distributions. Each point on the PCA plot represents one protein. Filled circles are the original protein markers used in classification, hollow circles show new locations as assigned by the SVM TL classifier. The 4 proteins GTR3_MOUSE, SNTB2_MOUSE, PAR6B_MOUSE and ADA17_MOUSE that were found in the SVM TL method and not in an SVM classification with LOPIT only are highlighted.