MAPK9 Gene (JNK2): Function, Expression, Mutations & Disease Associations | Biomedical Database

MAPK9 (Mitogen-Activated Protein Kinase 9) encodes a member of the mitogen-activated protein kinase (MAPK) family, specifically the c-Jun N-terminal kinase (JNK) subfamily. The encoded protein, JNK2, is a serine/threonine kinase that responds to cellular stress, inflammatory cytokines, and environmental stimuli. It phosphorylates transcription factors such as c-Jun, ATF2, and p53, regulating processes including apoptosis, proliferation, differentiation, and immune responses. Alternative splicing produces multiple isoforms with distinct functions. MAPK9 is implicated in various cancers, neurodegenerative diseases, and inflammatory conditions.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• MAPK signaling pathway

• JNK signaling pathway

• Fc epsilon RI signaling pathway

• T cell receptor signaling pathway

• Toll-like receptor signaling pathway

• Apoptosis

• Neurotrophin signaling pathway

• Insulin signaling pathway

The MAPK9 protein (JNK2) is a 424-amino-acid serine/threonine kinase with a molecular weight of approximately 48 kDa. It contains a conserved kinase domain and a T-loop with Thr-Pro-Tyr (TPY) motif, which is phosphorylated by upstream kinases (MKK4/MKK7) for activation. JNK2 exists in multiple isoforms (e.g., JNK2α1, JNK2α2, JNK2β1, JNK2β2) due to alternative splicing, differing in substrate specificity and subcellular localization. It primarily localizes to the cytoplasm and nucleus, where it phosphorylates transcription factors (c-Jun, ATF2, Elk-1) and other substrates, regulating gene expression. JNK2 also interacts with scaffold proteins (e.g., JIP1) to modulate signaling specificity. Its activity is tightly regulated by phosphatases and ubiquitination.