MKP-1 functions as a signaling node for the MAPKs. The MAPKs are dephosphorylated by MKP-1, and depending upon which MAPK is targeted, a combination of dephosphorylation events can occur. In addition, the substrates of the MAPKs can be phosphorylated by more than one MAPK, the combination of these phosphorylation events can evoke variable functional effects. The outcome of MKP-1 dephosphorylation of the MAPKs can result in a number of different functional outcomes from a particular phosphorylated MAPK substrate indicated hypothetically as “Responses 1–7”,.