A Src-astic response to mounting tension

The nerve growth cone binds to a complex array of guidance cues in its loca l environment that influence cytoskeletal interactions to control the direc tion of subsequent axon outgrowth. How this occurs is a critical question a nd must certainly involve signal transduction pathways. The paper by Suter and Forscher (2001, this issue) begins to address how one such pathway, an Src family tyrosine kinase, enhances cytoskeletal linkage to apCAM, a permi ssive extracellular cue for Aplysia growth cones. Interestingly, they show that applied tension increases this kinase's localized phosphorylation that in turn further strengthens linkage. This suggests a potential positive fe edback mechanism for amplifying and discriminating guidance information to guide growth cone motility.