Fig. 4

Protein-protein interaction networks of upregulated proteins associated with primary Sjögren’s syndrome detected in tear fluid. Two protein-protein interaction networks are visualised. One is central in the formation of the cytoskeleton and cell migration, while the other is involved in redox reactions and oxidative stress and contains one out of the five most upregulated proteins, as indicated with red circles (Table 5), namely thioredoxin-dependent peroxidase reductase (PRDX3). The Search Tool for the Retrieval of Interacting Genes/Proteins (http://string-db.org/) was used to generate the networks, where potential interactions of proteins with medium confidence are shown. The different clusters are indicated by the same colour. The colour of the connecting lines indicates the type of evidence used in predicting the associations (red gene fusion, yellow text-mining extracted from literature, purple protein-protein interaction datasets, light blue protein interaction groups, black linked across species). APEX1 DNA (apurinic or apyrimidinic site) lyase, CPNE1 copine, ACO2 aconitate hydratase, LMO7 LIM domain only protein 7