  Cells are constantly exposed to fluctuating environmental conditions.
External signals are sensed, processed and integrated by cellular signal
transduction networks, which translate input signals into specific cellular
responses by means of biochemical reactions. These networks have a complex
nature, and we are still far from having a complete characterization of the
process through which they integrate information, specially given the noisy
environment in which that information is embedded. Guided by the many instances
of constructive influences of noise that have been reported in the physical
sciences in the last decades, here we explore how multiple signals are
integrated in an eukaryotic cell in the presence of background noise, or
chatter. To that end, we use a Boolean model of a typical human signal
transduction network. Despite its complexity, we find that the network is able
to display simple patterns of signal integration. Furthermore, our
computational analysis shows that these integration patterns depend on the
levels of fluctuating background activity carried by other cell inputs. Taken
together, our results indicate that signal integration is sensitive to
environmental fluctuations, and that this background noise effectively
determines the information integration capabilities of the cell.
