Physiological roles of mitogen-activated-protein-kinase-activated p38-regulated/activated protein kinase

Figure 1 Mammalian mitogen-activated protein kinase pathways. The conventional mitogen-activated protein kinase (MAPK) pathway has a tripartite composition in which MAPK kinase kinase (MAP3K) phosphorylates and activates MAPK kinase (MAP2K), which in turn phosphorylates and activates MAPK. The atypical MAPK pathway lacks this typical three-tiered cascade. Both conventional and atypical MAPKs can phosphorylate different substrates, including other protein kinases referred to as MAPK-activated protein kinases (MAPKAPKs). The stippled lines indicate that a bona fide in vivo link between these MAPKs and their MAPKAPKs remains controversial. ERK: Extracellular signal-regulated kinase; RSK: Ribosomal-S6-kinase; MNK: MAPK-interacting kinase; JNK: c-JUN N-terminal kinase; PAK: p21-activated protein kinase; MK: MAPK-activated protein kinase; NLK: Nemo-like kinase; PRAK: p38-regulated/activated protein kinase.