FIGURE 3.

Functional protein–protein network analysis of FOS gene using STRING database. (A) The protein–protein interaction network of FOS and 10 other proteins. Proteins are presented by network nodes of different colors. The edges between FOS and its predicted functional partners represent protein–protein associations. Categorized identification of protein–protein interactions using different methods are labeled by circles. Already known interactions can be found from curated databases or experimental results. Predicted interactions can come from text mining, co-expression, and protein homology. (B) Further functional enrichment analysis of the protein network in KEGG pathways. FOS, JUN, CREB1, and ATF2 are involved in the amphetamine pathway. Proteins closely interacting with FOS protein also participate in other psychoactive drug pathways, such as cocaine addiction and alcoholism. (C) KEGG functional enrichment analysis of all genes in the protein–protein interaction network.