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PROLACTIN-INDUCED TYROSINE PHOSPHORYLATION, ACTIVATION AND RECEPTOR ASSOCIATION OF FOCAL ADHESION KINASE (FAK) IN MAMMARY EPITHELIAL CELLS
Fenton, S E. AND L. G. Sheffield. PROLACTIN-INDUCED TYROSINE PHOSPHORYLATION, ACTIVATION AND RECEPTOR ASSOCIATION OF FOCAL ADHESION KINASE (FAK) IN MAMMARY EPITHELIAL CELLS. Presented at Prolactin Gordon Conference, Ventura, CA, Jan. 30-Feb. 4, 2000.
Prolactin-Induced Tyrosine Phosphorylation, Activation and Receptor
Association of Focal Adhesion Kinase (FAK) in Mammary Epithelial Cells.
Suzanne E. Fenton1 and Lewis G. Sheffield2. 1U.S. Environmental Protection
Agency, MD-72, Research Triangle Park, NC 27711, and
2Endocrinology/Reproductive Physiology Program, 1675 Observatory Drive,
University of Wisconsin, Madison, WI 53706.
The activity and tyrosine phosphorylation of focal adhesion kinase
(FAK) was induced by prolactin in mouse mammary epithelial cells.
Prolactin also increased activity of c-src and JAK2. Expression of kinase
inactive c-src prevented the prolactin-induced activation of FAK,
suggesting that c-src activation was required for FAK activation. Kinase
inactive JAK2 prevented the activation of both FAK and of c-src, suggesting
that c-src activation is downstream of JAK2 activation. Prolactin induced
an increased association of c-src and FAK with the prolactin receptor.
Although kinase inactive c-src prevented tyrosine phosphorylation and
activation of FAK by prolactin, it did not prevent the prolactin-induced
increase in association of c-src and FAK with prolactin receptor. In
contrast, a kinase inactive mutant of JAK2 prevented the prolactin-induced
increase in association of c-src and FAK with prolactin receptor, as well
as prolactin-induced activity of c-src and FAK. These results indicate
that prolactin increased activity of JAK2, which is required for both
association of c-src and FAK with the prolactin receptor signaling complex
and activation of c-src and FAK. (This abstract does not reflect EPA policy)