| Abstract | Examples include metabolism where a handful of building blocks mediate between multiple input nutrients and multiple output biomass components, and signaling networks where information from numerous receptor types passes through a small set of signaling pathways to regulate multiple output genes. |
| Introduction | Studies of other biological signaling networks such as epidermal receptor signaling [21], GPCR signaling [22], signaling in both the innate [23,24] and the adaptive immune system also documented bow-tie organizations [4,25]. |
| Introduction | hypothesized that the narrow intermediate layer in signaling networks may serve to distinguish between different sets of inputs and assigns the correct set of outputs for each. |