Fig. 1

Protein–protein interaction (PPI) network created using STRING. The nodes represent proteins and the edges represent protein–protein association. The edge confidence is set to high (0.700), and disconnected nodes are hidden in the network. The nodes common to the most enriched pathways, i.e., substance abuse receptors and neuroactive ligand–receptors, are highlighted. Nodes in blue represent nicotine addiction, nodes in green represent cocaine addiction, nodes in yellow represent morphine addiction and nodes in red represent neuroactive ligand–receptor interaction. The edges are coloured based on the following types of interactions: known interactions (turquoise—from curated databases, purple—experimentally determined), predicted interactions (bright green—gene neighbourhood, red—gene fusions, dark blue—gene co-occurrence) and others (yellow—text mining, black—co-expression, light blue—protein homology).The filled nodes show that the 3D structure of the protein is known or predicted