History Matters

Abstract
How do signaling networks within cells communicate with each other in order to respond to a vast array of external stimuli with the correct responses? In their Perspective, [Ingolia and Murray][1] discuss a new approach (Bhalla et al .) that elucidates the regulation of the MAPK signaling cascade in cultured cells and how cellular history contributes to this regulation. [1]: http://www.sciencemag.org/cgi/content/full/297/5583/948