The human protein-protein interaction network of aging-associated genes. A total of 261 aging-associated genes were assembled using the GenAge Human Database . Protein-protein interactions of the human interactome were collected from the 8.0 version of the STRING database  using physical contacts only. The network was visualized using the Cytoscape program . The degree (number of neighbors) of nodes is represented by the size of the circle and the font. Note the high number of signaling pathway proteins among hubs (nodes with degrees - and therefore size - much greater than average), exemplified by the MAPK/ERK and PI3K/AKT proteins.