. Proteins are the nodes and the edges are protein activation/inactivations, such as phosphorylation and dephosphorylation across a set of proteins. The network presented here reveals an up-regulation of the matrix metalloproteinase family members MMP1, 7, 9, 10, 12 as well as LCN2, IL-8 and CXCL1. Down-regulated genes within this network are RECK, COL4A5 and COL4A6. The colors of the nodes describe the regulated expression of genes within cholesteatoma compared to external auditory skin: red: up-regulated genes within cholesteatoma; green: down-regulated genes within cholesteatoma; grey: the gene for the protein is not in the microarray; The “Node Ranking” (Node-Size) describes the number of interactions. The bigger the nodes, the more interactions are represented for the protein in the network.