JNK, cytoskeletal regulator and stress response kinase? A Drosophila perspective

c-Jun N-terminal kinases (JNKs) are intracellular stress-activated signalli ng molecules, which are controlled by a highly evolutionarily conserved sig nalling cascade. In mammalian cells, JNKs are regulated by a wide variety o f cellular stresses and growth factors and have been implicated in the regu lation of remarkably diverse biological processes, such as cell shape chang es, immune responses and apoptosis. How can such different stimuli activate the JNK path way and what roles does JNK play in vivo? Molecular genetic a nalysis of the Drosophila JNK gene has started to provide answers to these questions, confirming the role of this molecule in development and stress r esponses and suggesting a conserved function for JNK signalling in processe s such as wound healing. Here, we review this work and discuss how future e xperiments in Drosophila should reveal the cell type-specific mechanisms by which JNKs perform their diverse functions. BioEssays 20:1009-1019, 1998. (C) 1998 John Wiley & Sons, Inc.