Precision networking: a look through the eyes of a fly

The establishment of the proper connectivity in the nervous system requires specific target selection between individual presynaptic and postsynaptic cells. It has been postulated that cell adhesion molecules likely participate in these local recognition events. However, the broad developmental roles of many of these molecules have presented an obstacle for loss-of-function analyses. A recent series of genetic studies in the Drosophila visual system has demonstrated roles for several cell adhesion molecules, including N-cadherin and the receptor protein tyrosine phosphatase LAR in proper synaptic targeting of photoreceptor axons.