Cover photograph (Copyright © 2000, American Society for Microbiology. All rights reserved.): The NG108 neuronal cell line does not normally express B-type Eph receptor tyrosine kinases. NG108 lines that stably express wild-type or mutant EphB2 receptors were established by transfection with EphB2 cDNA expression vectors. Neurite extension was induced by treatment with di-butyryl-cAMP, and the distribution of EphB2 receptors in transfected cells was visualized by immunofluorescence using EphB2 antibodies. The EphB2 receptor can be seen at the tips of neurites in growth cone-like structures, in a pattern that coincides with F-actin. Challenging these cells with clustered ephrinB1, which activates the EphB2 receptor tyrosine kinase, leads to cytoskeletal reorganization and neurite retraction. (See related article on p. 4791.)