Distribution of interactions and proteins over co-expression correlation and stability. Number of a) interactions and b) proteins in the human protein-protein interaction network within ranges of co-expression correlation coefficient and stability as indicated in the heat map. The values for interactions are those of the gene pairs of interacting proteins. The values for proteins are averaged across all the interactions they participate in. The absence of proteins or interactions (0 value) is indicated in gray in the heat map to allow for better visualization of outliers. The correlation between co-expression correlation and stability is low showing their independence as sources of information.