JNK Pathway

The c-Jun N-terminal kinase (JNK) family consists of three ubiquitously expressed members, termed JNK1, JNK2 and JNK3 (Fig. 1) (Roux and Blenis 2004). The JNKs are strongly activated in response to cytokines, selected G-protein coupled receptors (GPCR) and cell stress, such as inhibition of DNA or protein synthesis. JNK is phosphorylated by either MEK4 or MEK7, which are themselves phospho-rylated by several kinases, including MEKK1-4, MLK2/3 and DLK (Fig. 1). Following activation, JNK is translocated to the nucleus where it phosphorylates and upregulates several transcription factors, including c-Jun, ATF-2, STAT3 and HSF-1 (Roux and Blenis 2004). JNKs control apoptosis and the development of multiple cell types in the immune system.

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