Mitogen-activated protein kinase 8 (JNK1)

Mitogen‑activated protein kinase 8 is a serine/threonine-protein kinase encoded by the MAPK8 gene. It belongs to the c-Jun N-terminal kinases (JNK) subfamily within the larger mitogen‑activated protein kinases family. This enzyme acts as a central node integrating diverse cellular signals from cytokines and environmental stresses. Upon activation by upstream kinases such as MKK4/MKK7, it phosphorylates various transcription factors including components of AP‑1 like JUN and ATF2, regulating immediate early gene expression linked to cell fate decisions. It plays critical roles in processes such as cell proliferation, differentiation, programmed cell death/apoptosis—including responses to TNF-alpha and UV radiation—and immune system function through T-cell regulation. Dysregulation has been implicated in cancer progression, inflammatory conditions, autoimmune diseases, hepatitis C infection risk/modulation, and developmental disorders.

Other names

c-Jun N-terminal kinase 1JNK1c-jun NH2-terminal kinaseMAP kinase 8PRKM8SAPK gammaSAPK1CStress-activated protein kinase 1cStress-activated protein kinase JNK1

Drugs targeting mitogen‑activated protein kinase 8 typically act as ATP‑competitive inhibitors of its serine/threonine-protein kinase activity, thereby blocking downstream phosphorylation events involved in stress signaling and apoptosis. They may inhibit AP‑1 transcription factor activation or block pro-apoptotic signaling.