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			PubMed Journals: Biochem Biophys Res Commun

  Source:		PMID: 11676480


    		Biochem Biophys Res Commun. 2001 Nov
     		2;288(3):564-72.

			Physical and functional interactions between
			protein tyrosine phosphatase alpha, PI 3-kinase,
			and PKCdelta.

			Steták A(1), Csermely P, Ullrich A, Kéri
			G.

			Author Information
			(1) Department of Medical Chemistry, Peptide
			Biochemistry Research Group, Semmelweis University,
			Budapest, H-1088, Hungary. stetak@hotmail.com

			The somatostatin analogue, TT-232 inhibits
			cell proliferation and induces apoptosis in
			a variety of tumor cells both in vivo and
			in vitro. While the early transient activation
			of Erk/MAPK was found to be important for
			the induction of cell cycle arrest, the
			signaling pathway leading to the activation
			of Erk/MAPK had not been fully established.
			Here we present evidence that activation
			of the Erk/MAPK pathway by TT-232 involves
			PI 3-kinase, PKCdelta and the protein tyrosine
			phosphatase alpha (PTPalpha). We show a
			physical interaction of PI 3-kinase and
			PKCdelta with PTPalpha and show that the
			tyrosine phosphatase plays a role in the
			activation of MAPK. In this process, PTPalpha
			Ser-180 and Ser-204 phosphorylation is critical
			for the induction of phosphatase activity,
			which is required for dephosphorylation
			of pp60(c-src). Taken together, we demonstrate
			the physical and functional association
			between PI 3-kinase, PKCdelta and PTPalpha
			in a signaling complex that mediates the
			antitumor activity of the somatostatin analogue
			TT-232.

			Copyright 2001 Academic Press.

			DOI: 10.1006/bbrc.2001.5811 PMID: 11676480
			[Indexed for MEDLINE]

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