Animals Article Cluster Analysis Euler polyhedron formula Gene Regulatory Networks Hexagonal clustering Humans Signal Transduction TNF superfamily signaling animal biology branched DNA signal amplification assay cell interaction cell surface receptor cluster analysis clustering algorithm gene regulatory network geometry human mathematical model membrane receptor methyl accepting chemotaxis protein monocyte chemotactic protein 1 photoreceptor phototaxis signal amplification signal transduction tumor necrosis factor tumor necrosis factor receptor associated factor tumor necrosis factor receptor associated factor 2