Model of relationship between EphB2, FGFR, MAPK, and cell repulsion. The diagram depicts relationships deduced in the current study integrated with the results of other studies described in the Discussion. Baseline activation of EphB2 is kept low by LAR and other receptor PTPs, which also limit the amount of ephrin-induced phosphorylation. LAR is down-regulated by FGFR1 activation. In the absence of FGFR1 activation, there is a high level of activation of EphB2 by ephrinB1 involving a positive feedback loop mediated by the MAPK pathway; this positive loop is limited by the inhibition of MAPK by RasGAP. EphB2 activation triggers multiple pathways that promote cell repulsion, one of which involves the inhibition of R-Ras by RasGAP. After induction of Sprouty genes downstream of FGFR, there is inhibition of the positive MAPK loop downstream of EphB2. This shifts the response to inhibition of MAPK by EphB2 and a lower level of EphB2 activation and cell repulsion.