Control of cell adhesion is critical to many biological processes including axonal pathfinding and tumor cell invasion. Cell adhesion can be modulated by binding of membrane-bound ephrins to Eph receptors. Zou et al. report that signaling from the EphB2 receptor to integrins appears to be mediated by tyrosine phosphorylation of R-Ras, which in turn stimulates integrin activity. Eph receptors are themselves tyrosine kinases and, at least in cells overexpressing EphB2 and R-Ras, the receptor appears to phosphorylate R-Ras directly. Regulation by phosphorylation represents a new layer of control for members of the Ras family.
Zou, J., Wang, B., Kalo, M.S., Zisch, A., Pasquale, E.B., and Rouslahti, E. (1999) An Eph receptor regulates integrin activity through R-Ras. Proc. Natl. Acad. Sci. U.S.A. 96: 13813-13818. [Abstract] [Full Text]