Date Approved


Date Posted


Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department or School


Committee Member

Robert S. Winning, PhD

Committee Member

Glenn K. Walker, PhD

Committee Member

Tamara L. Greco, PhD


Eph receptors and their ligands, ephrins, have been implicated in many important developmental processes and in tumorigenesis. The activation of EphA4 receptors in the frog, Xenopus laevis, causes loss of cell adhesion, tight junctions, and stress fibers. Previous studies revealed that these receptors achieve their cellular effects at least in part by inhibiting RhoA GTPase. However, what links these GTPases with the EphA4 receptor remained unknown.

In an attempt to investigate involvement of the Src-like tyrosine kinase p59fyn in EphA4 signaling, a series of experiments was planned using the chimeric receptor EPP. The findings presented in this thesis indicate that the Srclike tyrosine kinase, p59fyn, acts as a functional link between the EphA4 receptor and RhoA GTPase in Xenopus laevis embryonic cells. Moreover, an activated EphA4 receptor achieves its cellular effects through activation of p59fyn, which in turn inhibits RhoA.

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