The riddle of MAP kinase signaling specificity.

Cells encounter an enormous variety of signals in their environments and must respond to each stimulus appropriately with changes in their genetic programs. Many of these external signals are transduced by a highly conserved eukaryotic signaling mechanism, the mitogen-activated protein kinase (MAPK) cascade. How are the myriad of inputs transduced accurately so that each evokes a specific response? One mechanism would be to have a distinct MAPK cascade for each signal; however, the situation appears to be more complicated.