0045-0007 Bluthgen.indd

For more than a decade, the MAPK (mitogen-activated protein kinase) cascade has been studied using mathematical modelling and quantitative experimentation [1]. The MAPK cascade relays the presence of extracellular stimuli such as growth hormones to the nucleus and controls the expression of hundreds of genes. MAPKs control major cell fate decisions such as proliferation, differentiation and apoptosis, mainly by inducing alterations in gene expression. In this chapter, we discuss how systems biology analysis provides insights into the functioning of this cascade. We show how this pathway assists the cell in responding properly to extracellular cues by filtering out sub-threshold stimuli, while efficiently transmitting physiologically relevant inputs. Several different receptors signal through the MAPK pathway even though they elicit opposite biological responses, thus raising the question of how specifi city is achieved in MAPK signalling. Experimental studies revealed that specifi c biological responses are encoded by quantitative aspects of the MAPK signal such as amplitude or duration. 1Both authors contributed equally to this chapter. 2 To whom correspondence should be addressed (email nils.bluthgen@manchester. ac.uk). © The Authors Journal compilation © 2008 Biochemical Society