Cells receive external signals (depicted in yellow) through sensing molecules--or receptors--(depicted in aqua) embedded in the cell membrane. This information is transmitted sequentially throughout the cell via signaling networks. Arrows indicate the direction of information flow between signaling molecules A, B, C, and D in this illustration. Bayesian network modeling can determine that molecules A and B are in the same pathway. It can also tell if the activity of molecule B relies on a signal from molecule A. In many cases, communication from outside the cell follows signaling pathways to the nucleus, where the information activates genes that control the cell's response.

Credit: Nicolle Rager, National Science Foundation