An intracellular signaling system involving the MAP kinase cascades (three-membered protein kinase cascades). Various upstream activators, which act in response to extracellular stimuli, trigger the cascades by activating the first member of a cascade, MAP KINASE KINASE KINASES; (MAPKKKs). Activated MAPKKKs phosphorylate MITOGEN-ACTIVATED PROTEIN KINASE KINASES which in turn phosphorylate the MITOGEN-ACTIVATED PROTEIN KINASES; (MAPKs). The MAPKs then act on various downstream targets to affect gene expression. In mammals, there are several distinct MAP kinase pathways including the ERK (extracellular signal-regulated kinase) pathway, the SAPK/JNK (stress-activated protein kinase/c-jun kinase) pathway, and the p38 kinase pathway. There is some sharing of components among the pathways depending on which stimulus originates activation of the cascade.

Synonyms: ERK Pathway, MEK-ERK Pathway, ERK Signal Tranduction Pathway, Kinase Pathway, p38, p38 Kinase Pathways, Pathways, p38 Kinase, Pathways, JNK Signaling, JNK Pathway, ERK1-2 Pathway, MAP Kinase Signaling System, MAP Kinase Modules, Cascade, MAP Kinase, Pathway, ERK1-2, Kinase Cascade, MAP, Pathway, JNK, Module, MAP Kinase, ERK1-2 Pathways, Signaling Pathways, JNK, JNK Signaling Pathways, MEK-ERK Pathways, Pathway, ERK, ERK1 2 Pathway, Pathways, ERK, p38 Kinase Signaling Pathway, Pathway, MEK-ERK, Pathways, MEK-ERK, Pathways, JNK, Kinase Pathways, p38, MAP Kinase Module, Pathway, JNK Signaling, Pathways, ERK1-2, ERK Pathways, JNK Pathways, Pathway, p38 Kinase, p38 Kinase Pathway, MAP Kinase Cascades, MAP Kinase Cascade, MEK ERK Pathway, Signaling Pathway, JNK, JNK Signaling Pathway, MAP Kinase Signaling Pathways, ERK1 and ERK2 Pathway, MAP Kinase Signaling Cascades